To see the other types of publications on this topic, follow the link: Nano electronics.
Dissertations / Theses on the topic 'Nano electronics'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Nano electronics.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Li, Elise Yu-Tzu. "Electronic structure and quantum conductance of molecular and nano electronics." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/65270.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2011.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 129-137).
This thesis is dedicated to the application of a large-scale first-principles approach to study the electronic structure and quantum conductance of realistic nanomaterials. Three systems are studied using Landauer formalism, Green's function technique and maximally localized Wannier functions. The main focus of this thesis lies on clarifying the effect of chemical modifications on electron transport at the nanoscale, as well as on predicting and designing new type of molecular and nanoelectronic devices. In the first study, we suggest and investigate a quantum interference effect in the porphyrin family molecules. We show that the transmission through a porphyrin molecule at or near the Fermi level varies by orders of magnitude following hydrogen tautomerization. The switching behavior identified in porphyrins implies new application directions in single molecular devices and molecular-size memory elements. Moving on from single molecules to a larger scale, we study the effect of chemical functionalizations to the transport properties of carbon nanotubes. We propose several covalent functionalization schemes for carbon nanotubes which display switchable on/off conductance in metallic tubes. The switching action is achieved by reversible control of bond-cleavage chemistry in [1+2] cycloadditions, via the 8p 3 8s p 2 rehybridization it induces; this leads to remarkable changes of conductance even at very low degrees of functionalization. Several strategies for real-time control on the conductance of carbon nanotubes are then proposed. Such designer functional groups would allow for the first time direct control of the electrical properties of metallic carbon nanotubes, with extensive applications in nanoscale devices. In the last part of the thesis we address the issue of low electrical conductivity observed in carbon nanotube networks. We characterize intertube tunneling between carbon nanotube junctions with or without a covalent linker, and explore the possibility of improving intertube coupling and enhance electrical tunneling by transition metal adsorptions on CNT surfaces. The strong hybridization between transition metal d orbitals with the CNT [pi] orbitals serves as an excellent electrical bridge for a broken carbon nanotube junction. The binding and coupling between a transition metal atom and sandwiching nanotubes can be even stronger in case of nitrogendoped carbon nanotubes. Our studies suggest a more effective strategy than the current cross-linking methods used in carbon nanotube networks.
by Elise Yu-Tzu Li.
Ph.D.
2
Lau, Chit. "Single-molecule electronics with graphene nano-electrodes." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:bb412c5c-67a2-4c8f-9ba7-38daee151d21.
Full textAbstract:
Single-molecule electronics have attracted widespread attention for both basic scientific interests and potential in technological applications. However, development has been limited by the difficulty in fabricating robust nano-electrodes suitable for contacting individual molecules. Carbon based materials have recently emerged as alternative electrode materials and possess several distinct advantages over conventional gold based electrodes. This DPhil project is undertaken with the goal of developing graphene nano-electrodes and the subsequent fabrication and characterisation of graphene based single-molecule devices. By combining the best of two prevalent approaches for fabricating graphene nano-gaps: feedback controlled electroburning and plasma etching, it is possible to produce graphene nano-gap with sizes 1-2 nm. The fabrication procedure is performed at room temperature and in ambient conditions with a high yield. Furthermore, arrays can be produced which makes the technique suitable for integration with conventional semiconductor technologies for scalable applications. The graphene nano-electrodes are used to fabricate single-molecule transistors using porphyrin molecules. Due to the stability of the graphene nano-electrodes, the porphyrin single-molecule transistors show reproducible single-electron charging behaviour even at room temperature. High bias and gate transport spectroscopy can be performed where the excited energy spectrum of the molecule is measured. Graphene-fullerene single-molecule transistors are studied. We observe electron avalanche transport and redox-dependent Franck-Condon blockade as a result of the strong electron-vibron coupling and weak vibronic relaxation of the system. The vibrational modes of the molecule are found to be due to both intrinsic vibrational and center-of-mass motion as verified by transport spectroscopy, Raman spectroscopy and DFT calculations. The current stability diagram of our device compares well with a rate equation model from which we extract the electron-vibron coupling constant.
3
Melouki, Aissa. "Defect and fault tolerance techniques for nano-electronics." Thesis, University of Southampton, 2011. https://eprints.soton.ac.uk/185987/.
Full textAbstract:
Nanotechnology-based devices are believed to be the future possible alternative to CMOS-based devices. It is predicted that the high integration density offered by emerging nanotechnologies will be accompanied by high manufacturing defect rates and high operation-time fault rates. This thesis is concerned with developing defect and fault tolerance techniques to address low manufacturing yield due to permanent defects and reduced computational reliability due to transient faults projected in nanoscale devices and nanometre CMOS circuits. The described research makes four key contributions. The first contribution is a novel defect tolerance technique to improve the manufacturing yield of nanometre CMOS logic circuits. The technique is based on replacing each transistor by an N2-transistor structure (N ≥ 2) that guarantees defect tolerance of all (N−1) defects. The targeted defects include stuck-open, stuck-short and bridging defects. Extensive simulation results using ISCAS benchmark circuits, show that the proposed technique achieves manufacturing yield higher than recently proposed techniques and at a reduced area overhead. The second contribution is two new repair techniques, named Tagged Replacement and Modified Tagged Replacement, to improve the manufacturing yield of nanoscale cross-bars implementing logic circuits as look-up tables (LUTs). The techniques are based on highly efficient repair algorithms that improve yield by increasing the resolution of repair. Simulation results show that the proposed techniques are able to provide higher levels of defect tolerance and have lower redundancy requirements than recently reported techniques. Another popular crossbar-based circuit implementation is nanoscale programmable logic arrays (PLAs). The third contribution is a probabilistic defect tolerance design flow that improves the manufacturing yield of nanoscale PLAs and significantly reduces post-fabrication test and diagnosis time. This is achieved by limiting defect diagnosis to the nanowire level rather than the crosspoint level as in previously proposed graph-based techniques. The final contribution involves improving both manufacturing yield and computational reliability of nanoscale crossbars implementing logic circuits as LUTs. This is achieved by combining Hamming and Bose-Chaudhuri-Hocquenghem (BCH) codes together or with N-Modular Redundancy and Bad Line Exclusion techniques. Simulation results show a significant improvement in fault tolerance by the proposed techniques (targeting fault rates upto 20%) when compared to previously reported single coding schemes
4
Jiang, Jun. "A Quantum Chemical View of Molecular and Nano-Electronics." Doctoral thesis, Stockholm : Biotechnology, Kungliga tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4335.
Full text
5
Joo, Sung Chul. "Adhesion mechanisms of nano-particle silver to electronics packaging materials." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31730.
Full text
6
Jiang, Jun. "A generalized quantum chemical approach for nano- and bio-electronics." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-286.
Full text
7
Simpson, Grant J. "Quinone derivatives as novel single-molecule components for nano-electronics." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6309.
Full textAbstract:
In this thesis, quinone derivative molecules supported on a Cu(110) surface are studied using scanning tunnelling microscopy (STM). The experimentally investigated system is based on the bistable nature of these compounds, and so the work is introduced in the wider context of molecular electronics (Chapter 1). The theory and experimental techniques are also described (Chapters 2 and 3). In Chapter 4 the switching behaviour of azophenine (AP) and azotolyline (AT) is characterised using STM imaging and spectroscopy, and is demonstrated to be based on a hydrogen tautomerisation reaction. The activation energy for switching is quantified by measurement of the rate of switching as a function of varying bias voltage, and the process is determined to be stimulated by inelastic electron tunnelling. The reaction pathway is also revealed using theoretical modelling. Chapter 5 focusses on the condensed phase of AP on the Cu(110) surface. The switching behaviour is found to be largely quenched in the self- assembled phase, so statistical analyses of the AP-AP and AP-Cu interactions are conducted in order to try to explain this. Chapter 6 returns to the study of isolated AP molecules and investigates the spatial dependence of the switch with respect to the location of electronic excitation. It is shown that the final state of the molecule can be accurately selected by exciting specific functional groups within the molecule. This control originates from the non- degenerate reaction pathways for the sequential transfer of the two tautomeric protons. The work is then discussed in terms of future outlook and potential applications for bistable molecules.
8
Froberg, James Steven. "Single-Molecule Studies of Intermolecular Kinetics Using Nano-Electronics Circuits." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31915.
Full textAbstract:
As science and medicine advance, it becomes ever more important to be able to control and analyze smaller and smaller bioparticles all the way down to single molecules. In this dissertation several studies aimed at improving our ability to manipulate and monitor single biomolecules will be discussed.
First, we will discuss a study on developing a way to map dielectrophoresis with nanoscale resolution using a novel atomic force microscopy technique. Dielectrophoresis can be applied on nanoparticles through micron-scale electrodes to separate and control said particles. Therefore, this new method of mapping this force will greatly improve our ability to manipulate single biomolecules through dielectrophoresis.
The next two studies discussed will be aimed at using carbon nanotube nanocircuits to monitor single protein kinetics in real time. Drug development and delivery methods rely on the precise understanding of protein interactions, thus creating the need for information on single protein dynamics that our techniques provides. The proteins studied in these sections are MMP1 and HDAC8, both of which are known targets of anti-cancer drugs.
Finally, we developed a new strategy for diagnosing pancreatic cancer. Our strategy involves using graphene nanotransistors to detect exosomes released from the pancreatic tumor. The ability to reliably diagnose pancreatic cancer before it reaches metastasis would greatly improve the life expectancy of patients who develop this condition. We were able to test our technique on samples from a number of patients and were successfully able to distinguish patients with pancreatic cancer from noncancerous patients.
9
Ganti, Srinivas. "Low resistance metal semiconductor contacts : low power nano-electronics and sensing." Thesis, University of Newcastle upon Tyne, 2018. http://hdl.handle.net/10443/4093.
Full textAbstract:
Metal semiconductor (MS) contacts are essential in nearly every electronic device. High electrical contact resistance degrades device performance, especially at smaller device geometries. The contact resistance normally scales inversely with the cross-sectional area of the MS contact, and this results in poor electrical conduction in small geometries. Additionally, experiments confirm that surface effects dominate over bulk properties, especially at nanoscale geometries. These conditions impose several restrictions in implementing various device technologies. The electronic properties of metal-semiconductor contacts in some important semiconductors such as Si, Ge, GaAs, among others are found to be largely insensitive to the metal workfunction and semiconductor doping level, due to a phenomenon called Fermi level pinning (FLP). FLP can severely degrade device performance, and creates several fabrication challenges. Many semiconductors lose their applicability in mainstream electronics due to restrictions imposed by this effect. FLP effects are practically observed in many semiconductors doped below 1019 cm−3 and are most pronounced in lightly doped and (~intrinsic) pure crystals. This thesis explores material engineering methods to improve contact to semiconductors, without resorting to heavy doping. Large area metal contacts (length/ diameter (d)~ 50-300 μm) are fabricated on Si and Ge. Three key approaches are investigated: (1) Modifying interface dipoles and blocking Metal Induced Gap States (MIGS) using ~ nm thick charged oxide interlayers, implementing planar metal interlayer semiconductor (MIS) contacts (Chapter 4). (2) Exploiting geometric field enhancement in nanostructured hybrid contacts (Chapter 5) and (3) Exploiting voltage controlled non-equilibrium electron heating in island metal films. The contacts produced by these methods (2) and (3) are the first experimental demonstrations to show that limitations imposed by FLP can be overcome by modifying the contact material geometry alone, without using heavy doping. Applying mV range bias to these metallizations causes hot carrier emission from these contact's nanostructured surfaces. Hot carriers are non-equilibrium, energetic carriers that easily overcome the FLP effect in the semiconductor. High conductivity is observed due to the hot carrier effect over a broad range of temperatures -from 4.2 K, tested up to 500 K- despite using low doping in the semiconductor (ND ~ 6.4 × 1014 cm−3). Novel transport processes are revealed by hot carrier tunnelling and emission mechanisms, which improve conductivity in semiconductors, and will potentially be applicable to other low dimensional materials as well. The results in Chapter 5 show an interesting demonstration of hot carrier edge scaling current injection used to achieve Ohmic contact to low doped n-Ge. This contact scheme presents a ii promising alternative to improving conductivity extrinsically, without using heavy doping, and in a scalable manner. Chapter 6 also contains a proof of concept demonstration. It is shown that closely spaced networks of metal nano-islands of critical dimensions are susceptible to non-equilibrium electron heating, when they receive power in the form of voltage controlled tunnel current. This leads to elevated electron temperatures (~103 K) relative to a cold lattice (at ambient temperature). Hot carriers easily overcome small (few eV) electrostatic barriers e.g. Schottky barrier. Consequently, Ohmic conduction is observed at room temperature, and near ballistic hot carrier conduction is observed at 4.2 K through the entire low doped wafer (thickness 0.5 mm, ND ~ 6.4 × 1014 cm−3). The wide scope of these findings may find promising applications in nanoelectronic engineering and applied science. There is considerable incentive to continue the research, and obtain a wider range of materials capable of similar effects, described further in the thesis outlook (Chapter 7). Advancing this research further will translate to applications in high speed switching, sensing, optoelectronics and energy harvesting. It is anticipated that these technologies will be applicable to many semiconductors and can be adapted into heterostructures, using advanced fabrication methods.
10
Arab, Hassani Faezeh. "Resonant nano-electro-mechanical sensors for molecular mass-detection." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/336335/.
Full textAbstract:
This research is conducted as a part of EU FP7 project entitled NEMSIC (hybrid nanoelectro-mechanical/integrated circuit systems for sensing and power management applications) with project partners, EPFL, TU Delft, IMEC-NL, CEA-LETI, SCIPROM, IMEC-BE, Honeywell Romania, and HiQSCREEN. Nano-electro-mechanical (NEM) sensors are getting an increased interest because of their compatibility with “In-IC” integration, low power consumption and high sensitivity to applied force, external damping or additional mass. Today, commercial biosensors are developed based on mass-detection and electro-mechanical principles. One of the recent commercial mass-detection biosensors is a quartz crystal microbalance (QCM) biosensor which achieves the mass sensitivity of a few tens pico g/Hz. The newly developed in-plane resonant NEM (IP R-NEM) sensor in this thesis achieves the mass sensitivity less than zepto g/Hz that is over nine orders smaller than that of the commercial QCM sensor using a much smaller sensing area compared to the QCM sensor. This fact will make the IP-RNEM sensor a world-unique sensor that shows a very high sensitivity to a very small change in mass. The stated mass sensitivity is achieved by modelling the functionalization and detection processes of the suspended beam. For modelling the linker molecules in the functionalization process, a conformal coating layer in different configurations are added to the suspended beam and the sparse distribution of target molecules in the detection process is modeled by changing the density of the coating layer. I would like to clarify that the scaling rule of the mass responsivity is given by k4 regardless of the different functionalization configurations. I develop a completely new hybrid NEM-MOS simulation technology which combines three-dimensional finite element method (3D FEM) based NEM device-level simulation and circuit-level simulation for NEM-MOS hybrid circuits. The FEM device-level simulation module also includes new modelling of selfassembled monolayer for surface functionalization as well as adsorb ed molecules to be detected and facilitates quantitative evaluation of mass responsivity of designed NEM sensor devices. The basic part of the sensor, the NEM structure, includes a suspended beam and two side electrodes and that is fabricated at the Southampton Nanofabrication Centre (SNC). The fabrication at SNC includes a new sensor that uses a free-free beam that improves the quality factor up to five orders of magnitude at room temperature and atmosphere based on the numerical results. The IP R-NEM sensor consists of a suspended beam that is integrated with an in-plane MOSFET and is fabricated by CEA-LETI. The monolithically integrated NEM with the MOSFET on the same SOI layer for the sensor is a real breakthrough which makes it a potential low-cost candidate among the mass-detection based sensors. With respect to the conducted radio-frequency (RF) characterization for nano-wire devices in collaboration with the Tokyo Institute of Technology and NEM structures, the designing of an RF contact pad to reduce the effect of parasitic frequencies and doing the measurement at high vacuum to reduce the motional resistance and increase the quality factor are necessary for the characterization of devices with nano-scale dimensions. The integrated MOSFET in the IP RNEM sensor amplifies the output transmission signal from the resonating beam by its intrinsic gain. The fabricated sensors show a three orders of magnitude larger gain than that of the previously proposed resonant suspended gate FETs by biasing the MOSFET at the optimized voltage biases that are found based on the DC characterization of MOSFETs.
11
Yuan, Xiaoyan. "Full-Wave Analyses of Nano-Electromechanical Systems Integrated Multifunctional Reconfigurable Antennas." DigitalCommons@USU, 2009. https://digitalcommons.usu.edu/etd/443.
Full textAbstract:
This thesis work builds upon the theoretical studies and full-wave analysis of radio frequency micro- and nano-electromechanical systems (RF M/NEMS) integrated multi-functional reconfigurable antennas(MRAs). This is a part of the overall M/NEMS research efforts performed in the RF NEMS Laboratory at USU, which includes design, microfabrication, test, and characterization of M/NEMS integrated congitive wireless communication systems (fig. A.1).
The thesis work focuses on two MRAs. 1) A triple bands patch antenna which can operate at 800, 2400, and 4900 MHz in response to public safety wireless communication systems. 2) A multi-frequency multi-polarization MRA for wireless personal area networking application (WPAN) operating at 57-64 GHz frequency range
12
Athmakur, Abhiram Goud. "Substrate Heating During Channel Formation in Nano Scale MOSFET." Thesis, University of Louisiana at Lafayette, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553872.
Full textAbstract:
This thesis focuses on energy considerations in the MOSFET when we supply a bias to it. We also notice that the length of the MOSFET gets smaller and smaller then for a small release or exchange of energy that may take place in a MOS transistor which can cause a change in the temperature. We have investigated that there is a change in the temperature of the MOSFET when we supply bias to it as we keep reducing the length of the channel. The change in the temperature of the MOSFET is calculated theoretically.
13
ZHU, XIAOSHAN. "NANO ELECTROCHEMICAL SENSOR AND ITS MEASUREMENT ELECTRONICS WITH A DYNAMIC TRANSDUCTION MECHANISM." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1122989975.
Full text
14
Kawatkar, Prasanna Ulhas. "Energy of Formation of Step Junctions at Nano Dimensions." Thesis, University of Louisiana at Lafayette, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1553878.
Full textAbstract:
Planar transistors have been the important building block of integrated circuits for decades, during which the size of transistors has steadily decreased. We will evaluate energy released due to recombination and also evaluate energy stored in the electric field for the step junction case, and then calculate the net energy of formation for the step junction. Also, we have calculated the change in temperature due to the energy of formation.
15
Markov, Stanislav Nikolaev. "Gate leakage variability in nano-CMOS transistors." Thesis, University of Glasgow, 2009. http://theses.gla.ac.uk/771/.
Full textAbstract:
Gate leakage variability in nano-scale CMOS devices is investigated through advanced modelling and simulations of planar, bulk-type MOSFETs. The motivation for the work stems from the two of the most challenging issues in front of the semiconductor industry - excessive leakage power, and device variability - both being brought about with the aggressive downscaling of device dimensions to the nanometer scale. The aim is to deliver a comprehensive tool for the assessment of gate leakage variability in realistic nano-scale CMOS transistors. We adopt a 3D drift-diffusion device simulation approach with density-gradient quantum corrections, as the most established framework for the study of device variability. The simulator is first extended to model the direct tunnelling of electrons through the gate dielectric, by means of an improved WKB approximation. A study of a 25 nm square gate n-type MOSFET demonstrates that combined effect of discrete random dopants and oxide thickness variation lead to starndard deviation of up to 50% (10%) of the mean gate leakage current in OFF(ON)-state of the transistor. There is also a 5 to 6 times increase of the magnitude of the gate current, compared to that simulated of a uniform device. A significant part of the research is dedicated to the analysis of the non-abrupt bandgap and permittivity transition at the Si/SiO2 interface. One dimensional simulation of a MOS inversion layer with a 1nm SiO2 insulator and realistic band-gap transition reveals a strong impact on subband quantisation (over 50mV reduction in the delta-valley splitting and over 20% redistribution of carriers from the delta-2 to the delta-4 valleys), and enhancement of capacitance (over 10%) and leakage (about 10 times), relative to simulations with an abrupt band-edge transition at the interface.
16
Jafri, Syed Hassan Mujtaba. "Building Systems for Electronic Probing of Single Low Dimensional Nano-objects : Application to Molecular Electronics and Defect Induced Graphene." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-160630.
Full textAbstract:
Nano-objects have unique properties due to their sizes, shapes and structure. When electronic properties of such nano-objects are used to build devices, the control of interfaces at atomic level is required. In this thesis, systems were built that can not only electrically characterize nano-objects, but also allow to analyze a large number of individual nano-objects statistically at the example of graphene and nanoparticle-molecule-nanoelectrode junctions. An in-situ electrical characterization system was developed for the analysis of free standing graphene sheets containing defects created by an acid treatment. The electrical characterization of several hundred sheets revealed that the resistance in acid treated graphene sheets decreased by 50 times as compared to pristine graphene and is explained by the presence of di-vacancy defects. However, the mechanism of defect insertion into graphene is different when graphene is bombarded with a focused ion beam and in this case, the resistance of graphene increases upon defect insertion. The defect insertion becomes even stronger at liquid N2 temperature. A molecular electronics platform with excellent junction properties was fabricated where nanoparticle-molecule chains bridge 15-30nm nanoelectrodes. This approach enabled a systematic evaluation of junctions that were assembled by functionalizing electrode surfaces with alkanethiols and biphenyldithiol. The variations in the molecular device resistance were several orders of magnitude and explained by variations in attachment geometries of molecules. The spread of resistance values of different devices was drastically reduced by using a new functionalization technique that relies on coating of gold nanoparticles with trityl protected alkanedithiols, where the trityl group was removed after trapping of nanoparticles in the electrode gap. This establishment of a reproducible molecular electronics platform enabled the observation of vibrations of a few molecules by inelastic tunneling spectroscopy. Thus this system can be used extensively to characterize molecules as well as build devices based on molecules and nanoparticles.
17
Roy, Gareth D. "Simulation of intrinsic parameter fluctuations in nano-CMOS devices." Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/6202/.
Full textAbstract:
As devices are scaled to gate lengths of sub 100 nm the effects of intrinsic parameter fluctuations will become increasingly important. This work presents a systematic simulation study of intrinsic parameter fluctuations, consisting of random dopant fluctations, line edge roughness and oxide thickness fluctuations, in a real 35 nm MOSFET developed by Toshiba. The simulations are calibrated against experimental data for the real device and it is found that discrete random dopants have the greatest impact on both the threshold voltage and leakage current fluctuations with a σVT of 33.2mV and a percentage increase in the average leakage current of 50%. Line edge roughness has the second greatest impact with a σVT of 19mV and percentage increase in the average leakage current of 45.5%. The smallest impact is caused by oxide thickness variations resulting in a σVT of 1.8mV and a 13% increase in the average leakage current. The combined effects of pairs of fluctuations is also studied, showing that these sources of intrinsic parameter fluctuations are statistically independent and a calculated σVT of 39mV is given for all of the sources combined. This value is on par with that reported in literature for the 90 nm technology node.
18
Adamu-Lema, Fikru. "Scaling and intrinsic parameter fluctuations in nano-CMOS devices." Thesis, University of Glasgow, 2005. http://theses.gla.ac.uk/7086/.
Full textAbstract:
The core of this thesis is a thorough investigation of the scaling properties of conventional nano-CMOS MOSFETs, their physical and operational limitations and intrinsic parameter fluctuations. To support this investigation a well calibrated 35 nm physical gate length real MOSFET fabricated by Toshiba was used as a reference transistor. Prior to the start of scaling to shorter channel lengths, the simulators were calibrated against the experimentally measured characteristics of the reference device. Comprehensive numerical simulators were then used for designing the next five generations of transistors that correspond to the technology nodes of the latest International Technology Roadmap for Semiconductors (lTRS). The scaling of field effect transistors is one of the most widely studied concepts in semiconductor technology. The emphases of such studies have varied over the years, being dictated by the dominant issues faced by the microelectronics industry. The research presented in this thesis is focused on the present state of the scaling of conventional MOSFETs and its projections during the next 15 years. The electrical properties of conventional MOSFETs; threshold voltage (VT), subthreshold slope (S) and on-off currents (lon, Ioffi ), which are scaled to channel lengths of 35, 25, 18, 13, and 9 nm have been investigated. In addition, the channel doping profile and the corresponding carrier mobility in each generation of transistors have also been studied and compared. The concern of limited solid solubility of dopants in silicon is also addressed along with the problem of high channel doping concentrations in scaled devices. The other important issue associated with the scaling of conventional MOSFETs are the intrinsic parameter fluctuations (IPF) due to discrete random dopants in the inversion layer and the effects of gate Line Edge Roughness (LER). The variations of the three important MOSFET parameters (loff, VT and Ion), induced by random discrete dopants and LER have been comprehensively studied in the thesis. Finally, one of the promising emerging CMOS transistor architectures, the Ultra Thin Body (UTB) SOl MOSFET, which is expected to replace the conventional MOSFET, has been investigated from the scaling point of view.
19
Roy, Tapashree. "Control and localisation of light with engineered nano-structures." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/369991/.
Full textAbstract:
In this thesis I present my research on nano-scale light control using several novel approaches. I have demonstrated a planar metal nano-structure with cylindrical symmetry that is designed to create a super-oscillation of electromagnetic waves to focus light down to sizes smaller than the Abbe diffraction limit. For the first time this super-oscillatory lens was experimentally used for imaging of nano-structures. A pair of 0:3λ diameter nano-holes with 0:16λ edge-to-edge separation were resolved. I have demonstrated a novel type of super-oscillatory lens which produces a continuous distribution of sub-wavelength light localisations extending over several wavelengths along the optical axis. This `optical needle' is also characterised by a large field of view. I have experimentally demonstrated a optical-needle-lens with 7µm depth of focus and 16% narrower than a diffraction-limited focal spot. I have characterised the point spread function of the above-mentioned super-oscillatory lenses, i.e., their ability to accurately image a point source. The images of the point source generated by these super-oscillatory lenses are at least 24% smaller than that produced by an ideal glass lens restrained by the Abbe diffraction limit. I have experimentally verified the imaging characteristics of the optical-needle-lens and demonstrated its ability to detect the off-axis placement of a point-like source. I have developed the nano-fabrication processes for manufacturing the super-oscillatory lenses on thin films of metals (Au, Al, Ti) using gallium focused-ion-beam milling technology. The focusing characteristics of the fabricated structures showed very good agreement with computational predictions. I have computationally shown that objects placed within the field of viewfocfocus of the optical-needle-lens can be imaged with super-resolution quality. This is a significant improvement over the sub-wavelength-step scanning imaging technique reported in this thesis for the other kind of super-oscillatory lens. For example, a super-oscillatory lens can resolve a `random' cluster of 0:15λ diameter nano-holes with the smallest edge-to-edge separation of 0.28λ. I have experimentally demonstrated the first prototype of a solid-immersion superoscillatory lens that promises to achieve a 50 nm hotspot with 405 nm illumination for applications in heat-assisted magnetic recording technology. I have demonstrated for the first time a planar diffraction grating for visible light designed by arranging meta-molecules to produce a periodic phase ramp. I have also demonstrated the first ever metamaterial-based planar lens-array that produced a 2D array of sub-wavelength foci. Finally, I have provided the first experimental evidence that photoluminescence of gold can be substantially enhanced by patterning the film with designed 2D nano-structured array (or, metamaterials). When resonant two-photon excitation is used the metamaterial enhances the photoluminescence by more than 76 times. I have also observed that the photoluminescence emission peaks are linked to the frequencies of absorption resonances in the metamaterials.
20
Maqina, Sinamandla Mvuyisi. "X-band antenna design for nano-satellite applications." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2703.
Full textAbstract:
Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2018.This research report discusses feasible designs of conformal antennas that provide a proof of concept for the French South African Institute of Technology’s future needs. The design is to be used in forthcoming space missions and the intention is to mount the antenna on the surface of a spacecraft. Hence, a low profile is mandatory along with good circular polarisation radiation characteristics. Microstrip patch antennas have been chosen for this purpose simply because they have low profile and conform to most structures, thus fulfilling the requirements stated above. All the designs that are featured in this thesis were modelled and validated using the electromagnetic simulation software FEKO and prototypes were built and tested. The simulations and measured results are supplemented by theory. Sometimes it can be challenging to design and develop an antenna that fulfils the required performance goals given the size and weight restrictions that are specified for nano-satellite technology. Therefore, the first phase of this project finds a good balance between the criteria set for CubeSat platforms and antenna performance. The second phase is validation. Single patch antennas and a sequential rotated patch array were designed, built and tested. The sequential rotated patch array offers considerable improvements in performance when compared to single patch antennas. For instance, the 3 dB axial ratio bandwidth increased to 9.6 % from 2 % when a sequential rotated array was used. The CubeSat normally flies in the inclined regions of the low Earth orbit (LEO). This area has high-energy auroral electron fluxes, in which the high-density electrons build up on ungrounded surfaces of spacecraft and cause discharge arcing. The discharge can affect the satellite operation and, in the worst case, cause permanent damage to the components. A mitigation technique by means of a bleeding path provides a quick route to ground and the space-qualified material that is used will ensure that the antenna is robust enough to survive this.
21
Hwang, Jung Yoon. "Spatial stochastic processes for yield and reliability management with applications to nano electronics." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1500.
Full textAbstract:
This study uses the spatial features of defects on the wafers to examine the
detection and control of process variation in semiconductor fabrication. It applies
spatial stochastic process to semiconductor yield modeling and the extrinsic reliabil-
ity estimation model. New yield models of integrated circuits based on the spatial
point process are established. The defect density which varies according to location
on the wafer is modeled by the spatial nonhomogeneous Poisson process. And, in
order to capture the variations in defect patterns between wafers, a random coeff-
cient model and model-based clustering are applied. Model-based clustering is also
applied to the fabrication process control for detecting these defect clusters that are
generated by assignable causes. An extrinsic reliability model using defect data and
a statistical defect growth model are developed based on the new yield model.
22
Hamedi, Mahiar. "Organic electronics on micro and nano fibers : from e-textiles to biomolecular nanoelectronics." Doctoral thesis, Linköpings universitet, Biomolekylär och Organisk Elektronik, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-17661.
Full textAbstract:
Research in the field of conjugated polymers (CPs) has led to the emergence of a number of interesting research areas and commercial applications, including solar cells, flexible displays, printed electronics, biosensors, e-textiles and more. Some of the advantages of organic electronics materials, as compared to their inorganic counterparts, include high elasticity, and mechanical flexibility, which allows for a natural integration of CPs into fabrics, making them ideal for e-texile. In this thesis, a novel approach for creating transistors is presented, through the construction of electrolyte gated transistors, directly embedded on functional textile fibers. Furthermore theoretical and experimental results of the integration of functional woven devices based on these transistors are shown. The realization of woven digital logic and design schemes for devices that can be placed inside living tissue, for applications such as neural communication, are demonstrated. Reducing feature sizes in organic electronics is necessity just as in conventional microelectronics, where Moore's law has been the most impressive demonstration of this over the past decades. Here the scheme of self-assembly (SA) of biomolecular/CP hybrid nano-structures is used for creating nano electronics. It is demonstrated that proteins in the form of amyloid fibrils can be coated with the highly conducting polythiophene derivative (PEDOT-S) through molecular self-assembly in water, to form conducting nanowire networks and nanodevices at molecular dimensions. In a second SA scheme, large area patterning of connected micro-nano lines and nano transistors from the conducting polymer PEDOT-S is demonstrated through assembly of these from fluids using soft lithography. Thereby the problems of large area nano patterning, and nano registration are solved for organic electronics. The construction of functional nanoscopic materials and components through molecular self-assembly has the potential to deliver totally new concepts, and may eventually allow cheap mass production of complex three dimensional nano electronic materials and devices.
23
Fanelli, Lucy Katharine. "Electronics for a Versatile and Robust Retarding Potential Analyzer for Nano-Satellite Platforms." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/49297.
Full textAbstract:
A retarding potential analyzer (RPA) is an instrument that, when mounted on a satellite in low-Earth orbit, makes in-situ measurements of ion density, temperature and speed relative to the satellite frame. The instrument works by changing the voltage on one of a set of grids and measuring a corresponding current generated by ions flowing through the grid, generating a function of current vs. voltage called an I-V curve. Traditionally, the size and power requirements of retarding potential analyzers has limited their use to larger satellites. In this thesis, the electrical design and basic testing of a retarding potential analyzer for use on resource- limited cubesat platforms are described.
The mechanical design of the retarding potential analyzer is first described, and the requirements of the electrical design are presented. The electrical requirements are based on both the characteristics of the ionosphereic flight environment, and on the size and power requirements typical of the small cubesat platforms for which the instrument is intended.
The electrical hardware is then described in detail. The digital design is reviewed as well, including the instrument's operating modes, command and data structure, and timing scheme.
Test data showing the basic functionality of the instrument are then presented. Bench tests validate the design by confirming its ability to control voltages and measure small currents. End-to-end tests were also performed in a vacuum chamber to mimic the ionospheric environment. These data are presented to show the ability of the RPA to meet or exceed its design specifications.Master of Science
24
Garrido, Torres José A. "Density functional theory investigations of molecules on surfaces : from nano-electronics to catalysis." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/15618.
Full textAbstract:
In this thesis, a wide breadth of topics related to the field of surface science are addressed using density functional theory (DFT). Specifically, five studies with relevance to molecular electronics and heterogeneous catalysis are presented, with a particular focus on interadsorbate interactions, reactivity and characterisation of molecules on transition metal surfaces. The first part of this work focuses on giving strong theoretical underpinning to the atomic-scale observations provided by scanning tunnelling microscopy (STM) experiments conducted by my group colleagues. The theoretical calculations presented here provide support to the experimental evidences but also serve to unravel information that is inaccessible from the experiments. On the one hand, the variety of results obtained in this thesis using standard DFT methods serve to highlight the capabilities of the computationally low-demanding methods for modelling processes occurring on metal surfaces. On the other hand, we notice that these workhorse methods in DFT have inherent limitations for providing an accurate description of some properties, in particular binding energies. This, further improvements in the level of theory are necessary for advancing the computational accuracy of standard DFT methods in materials science. The second part of this thesis is devoted to highlight the high level of accuracy obtained by the new theoretical approaches in the field of materials science. Due to the recent implementation of new algorithms combined with the increasing computer power that is available to the scientific community, these sophisticated methods are becoming more accessible for modelling solid-state systems. Here, the recent implementation of the random-phase approximation (RPA) for solids is employed to perform to benchmark study on the adsorption of benzene on different close-packed transition metal surfaces. The development of new theoretical tools is also essential to improve our predictive capabilities in surface science. A novel approach to correct vibrational intensities by including anharmonicities using density functional perturbation theory (DFPT) is proposed. The new method is tested for the adsorption of different organic molecules on various transition metal surfaces. The results obtained by this implementation demonstrate excellent improvements for predicting accurate spectra of molecules on surfaces.
25
Asadollahbaik, Asa. "The optical properties of nano-photonic biomimetic antireflective structures." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/314727/.
Full text
26
Rodenchuk, Christopher. "Carbon nano-material based saturable absorbers and their application to mode-locked lasers." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103571.
Full textAbstract:
The first part of this thesis presents the implementation of a passively mode-locked fiber ring laser incorporating single walled carbon nanotubes (SWNT). The laser was found to generate soliton pulses with pulsewidths on the order of 1 ps and bandwidths of 3.5 nm at a repetition rate of 10 MHz. Power dependent harmonic mode-locking was demonstrated, generating pulses with a repetition rate of up to 130 MHz. The second part of the thesis presents an attempt to determine if carbon nanoparticles, known as carbon black, exhibit similar nonlinear optical properties to other forms of carbon nano-materials, making them suitable for use in mode-locked lasers. The nonlinear measurements were inconclusive, however a Q-switched laser was demonstrated incorporating carbon black. The laser had power dependent pulsewidths on the order of 10 us, repetition rates on the order of 27 kHz and was wavelength tuneable in the region of 1545 to 1565 nm.Mode-locked lasers are ideally suited to generate ultrashort and high power laser pulses which have found uses in many fields. Passively mode-locked lasers require a nonlinear optical component known as a saturable absorber. Recently, carbon nano-materials, specifically carbon nanotubes and graphene have been shown to be promising saturable absorber materials around which passively mode-locked lasers can be implemented. The first part of this thesis presents an attempt to determine if carbon nanoparticles, known as carbon black, exhibit similar nonlinear optical properties to other forms of carbon nano-materials, making them suitable for use in mode-locked lasers. The second part of the thesis details the implementation of a fiber ring laser mode-locked with single walled carbon nanotubes (SWNT). The laser is characterised in the both the time and frequency domains under different intracavity power, and the various modes of operation are analysed.
27
Ravichandran, Karthik. "Nano-scale process and device simulation." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1125340288.
Full text
28
Sandison, Mairi Elizabeth. "Micro- and nano-electrode arrays for electroanalytical sensing." Thesis, Connect to e-thesis, 2004. http://theses.gla.ac.uk/1025/.
Full textAbstract:
Thesis (Ph.D.) - University of Glasgow, 2004.Includes bibliographical references (p. 183-203). Print version also available. Mode of access : World Wide Web. System requirements : Adobe Acrobat reader required to view PDF document.
29
Fenni, Magano Tweetheni Shidhika. "Estimation of the direction of arrival of signals from nano-satellites using antenna interferometry." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/1175.
Full textAbstract:
Thesis submitted in fulfilment of the requirements for the degree
Master of Technology: ELECTRICAL ENGINEERING
in the Faculty of Engineering
at the Cape Peninsula University of Technology
2014The thesis reports on the evaluation and comparison of various signal processing algorithms for estimating the direction of arrival (DOA) of a high frequency (HF) beacon signal from a CubeSat in Low Earth Orbit (LEO). The DOA of the HF beacon signal is expressed in terms of the two angles, azimuth ( α ) and elevation ( ). The azimuth and elevation angles of the received HF signal are calculated from the phase differences between signals observed at three elements of an L-shaped crossed-loop antenna array. The algorithms which were evaluated are the Zero Crossing (ZC), Cross Correlation (CC), Fast Fourier Transform (FFT) and Cross Power Spectral Density (CPSD) algorithms. A theoretical analysis was done to demonstrate that the phase differences at the radio frequency (RF) of the beacon are propagated to the baseband signals. The algorithms were thus tested using simulated baseband signals as would be derived from the RF signals intercepted by the three elements of an L-shaped crossed-loop antenna array. Gaussian noise with a given signal-to-noise ratio (SNR) was added to the simulated baseband signals. The algorithms were implemented in MATLAB. The criteria for the selection of the best algorithm were accuracy and speed. The standard deviation (SD) of the azimuth and elevation errors was used to measure the performance accuracy of each algorithm, while the computational time for a given number of samples and runs was used to express the speed of each algorithm. First the ZC, CC, FFT and CPSD algorithms were evaluated for various SNR values, and compared with respect to SD of the azimuth and elevation errors. The analysis of the simulations demonstrate that the FFT and CPSD algorithms outperform the ZC and CC algorithms by estimating the DOA with a small SD of errors even at the low SNR of 0 dB, where the noise amplitude is the same as the signal amplitude. The ZC algorithm estimates the DOA with a large SD of error at low SNR due to multiple ZC points occurring during the same cycle. The ZC algorithm breaks down when the SNR decreases below 35 dB. The accuracy of the ZC algorithm depends on the method by which the ZC points are detected. The CC algorithm breaks down when the SNR decreases below 10 dB. The CPSD and FFT algorithms break down when the SNR decreases below – 20 dB. However, at a high SNR of 40 dB and above, all the algorithms estimate the DOA with a SD of error smaller than 1˚ for the azimuth and elevation. Next, the ZC, CC, FFT and CPSD algorithms were compared with respect to computation time. The FFT was found to be the fastest algorithm. Although the CPSD and the FFT algorithms reach the same accuracy in the estimation of the DOA, the FFT was selected as the optimum algorithm due to its better computation time. Recommendations are made regarding the implementation of the proposed algorithms for real signals from the HF direction finding (DF) array. At the time of submission of this thesis, such signals were not yet available.
30
Allison, Matt. "Metrology and analysis of nano-particulate barium titanate dielectric material." Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/529.
Full text
31
de, Mendoza Bonmatí Paula. "Design and synthesis of new polyaromatic scaffolds for nano-scale applications." Doctoral thesis, Universitat Rovira i Virgili, 2010. http://hdl.handle.net/10803/9045.
Full textAbstract:
Design and Synthesis of New Polyaromatic Scaffolds for Nano-Scale ApplicationsResumen:
En la última década, el diseño y la síntesis de nuevos sistemas poliaromáticos han resultado de gran interés gracias a sus propiedades únicas y sus aplicaciones potenciales para la obtención de dispositivos electrónicos, y como precursores de fullerenos.
Hemos estudiado el mecanismo que procede a través de la activación del enlace C-H en la reacción intramolecular de arilación directa catalizada por paladio, para la formación de sistemas biarílicos, demostrando que la reacción procede a través de la abstracción del protón asistido por la base. Aplicando condiciones optimizadas hemos preparado la molécula C60H24 que al ser irradiada da lugar a la formación del fullereno C60, mediante la reacción de arilación directa formando seis nuevos enlaces C-C en una única etapa.
Además, en una colaboración interdisciplinar con físicos teóricos y experimentales, en el proyecto PicoInside, hemos participado en el diseño y la síntesis de moléculas poliaromáticas para su posterior aplicación como dispositivos electrónicos moleculares.
Abstract:
In the last decade, the design and synthesis of new polyaromatic scaffolds have attracted a broad interest due to their exceptional properties and their potential applications in material science like molecular electronic devices and as precursors of fullerene.
Based in the intramolecular palladium-catalyzed direct arylation reaction we developed new procedures as reliable tools for the biaryl coupling through C-H activation. Insight mechanistic studies showed a proton abstraction mechanism assisted by the base rather than activation of aromatic systems towards electrophilic attack. Applying optimized reaction conditions, formation up to six C-C bonds, and in situ dehydrogenation, allows for the synthesis of C60H24, crushed fullerene in one single step that upon laser irradiation leads to C60 fullerene.
Moreover, in an interdisciplinary collaboration with theoretical and experimental physicist, PicoInside project, we have participated in the design and synthesis of Y-shaped polyaromatic molecules required for single molecule electronic devices.
32
Gao, R. "Bias temperature instability modelling and lifetime prediction on nano-scale MOSFETs." Thesis, Liverpool John Moores University, 2018. http://researchonline.ljmu.ac.uk/8989/.
Full textAbstract:
Bias Temperature Instability (BTI) is one of the most important reliability concerns for Metal Oxide Semiconductor Field Effect Transistors (MOSFET), the basic unit in integrated circuits. As the development MOSFET manufacturing technology, circuit designers need to consider device reliability during design optimization. An accurate BTI lifetime prediction methodology becomes a prerequisite. Typical BTI lifetime standard is ten years, accelerated BTI tests under high stress voltages are mandatory. BTI modelling is needed to project BTI lifetime from high voltages (accelerated condition) to operating voltage. The existing two mainstream BTI models: 1). The Reaction-Diffusion (R-D) framework and 2). The Two-Stage model cannot provide accurate lifetime prediction. Quite a few fitting parameters and unjustifiable empirical equations are needed in the R-D framework to predict the lifetime, questioning its predicting capability. The Two-stage model cannot project device lifetime from high voltages to operating voltage. Moreover, the scaling down of MOSFET feature size brings new challenges to nano-scale device lifetime prediction: 1). Nano-scale devices’ current is fluctuating due to the impact of a single charge is increasing as MOSFET scaling down, repetitive tests need to be done to achieve meaningful averaged results; 2). Nano-scale devices have significant Device-to-Device variability, making the lifetime a distribution instead of a single value. In this work a comprehensive As-grown Generation (A-G) framework based on the A-G model and defect centric theory is proposed and successfully predicts the Time Dependent Variability and lifetime on nano-scale devices. The predicting capability is validated by the good agreement between the test data and predicted values. It is speculated that the good predicting capability is due to the correct understanding of different types of defects. In the A-G framework, Time Dependent Variability is experimentally separated into Within-Device Fluctuation and the averaged degradation. Within-Device Fluctuation can be directly measured and the averaged degradation can be modelled using the A-G model. The averaged degradation in the A-G model contains: Generated Defects, As-grown Traps and Energy Alternating Defects. These defects have different kinetics against stress time thus need separate modelling. Various patterns such as Stress-Discharge-Recharge, multi-Discharging-based Multiple Pulses are designed to experimentally separate these defects based on their different charging/discharging properties. Fast-Voltage Step Stress technique is developed to reduce the testing time by 90% for the A-G framework parameter extraction, making the framework practical for potential use in industry.
33
Chichenkov, Aleksandr. "Electrokinetic manipulation of micro to nano-sized objects for microfluidic application." Thesis, University of Liverpool, 2013. http://livrepository.liverpool.ac.uk/15933/.
Full textAbstract:
This thesis describes experimental and numerical investigations of various electrokinetic techniques on fluorescent particles, bacteria and protein motors. The aim of this work is to extend the knowledge on the object manipulation, which is an essential part of a practical microfluidic device. The dissertation consists of three major sections that contain novel approaches to object manipulation using electric fields. The effect of dielectrophoretic force on fluorescent particles is analysed first. Using an experimental setup with a controlled switch for the input signal, the theoretical framework for amplitude modulated responce of dielectrophoretic force is developed. Also presented is the image processing software for quantitative particle motion analysis. Another analysis of various electrokinetic techniques (dielectrophoresis, AC electroosmosis, AC electrothermal flow and electrophoresis) was carried out on Pseudomonas Fluorescence bacteria in a solution that supports its growth. These bacteria usually live in geometrically restricted spaces and so spatially confined transparent channels were created to mimic their natural environment. It was noted that in these conditions the motile bacteria do not experience the effect of dielectrophoretic force. The minimum frequency that can be applied to the solution without forming bubbles is too high to distinguish AC electroosmotic effect. Using the numerical simulation, however, the experimental setup that utilises the observed effect of electrophoresis and AC electrothermal flow is designed. The final study was carried out on protein molecular motors. The novel experimental setup to investigate the effect of the electric field on the actin filament motility on five different surfaces, covered with myosin II motors, was developed. The application of higher external electric fields resulted in different velocity increases on different surfaces. Using the numerical simulation, this difference is quantitatively explained by the variation of the number of motors on surfaces. Also presented is a novel method that enables determining the forces exerted by the population of active and resistive motors without the need of expensive equipment.
34
Caccamo, Sebastiano. "Innovative techniques for conformal doping of semiconductors for applications in micro- and nano-electronics." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/4171.
Full textAbstract:
This Ph.D. thesis is intended to provide a contribution to understanding some aspects of doping by MD through systematic experimental work.
In chapter 1, in order to better understand this work, the main aspects of semiconductor properties, the techniques commonly used for doping these materials and the MD are briefly recalled.
In chapter 2 some aspects of MD are discussed. In particular a physico-chemical characterization of molecular precursors in standard conditions, the role of the surface treatments and the role of the dilution of the precursor solution was examined.
In chapter 3, the results about the role of the deposition parameters in MD are discussed, focusing on the role of coating time and sampling time and on the role of the solvent and the molecular precursor.
Chapter 4 examines the results obtained by studying the effects of the post-deposition treatments. The following aspects are discussed in detail: the role of the annealing parameters: Temperature and time, the competition between evaporation and diffusion and the role of the cap layer.
In chapter 5 an example of application of MD to Si nanowires are investigated.
Finally, the results of this work and the perspectives of this activity are discussed and possible experimental approaches for the study of some unclear aspects in this thesis work are proposed.
These aspects were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), transmission electronic microscopy (TEM) and Raman Spectroscopy, electrical measurements were performed by spreading resistance profiles (SRP).
35
Azam, Touqeer. "Robust low-power digital circuit design in nano-CMOS technologies." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2512/.
Full textAbstract:
Device scaling has resulted in large scale integrated, high performance, low-power, and low cost systems. However the move towards sub-100 nm technology nodes has increased variability in device characteristics due to large process variations. Variability has severe implications on digital circuit design by causing timing uncertainties in combinational circuits, degrading yield and reliability of memory elements, and increasing power density due to slow scaling of supply voltage. Conventional design methods add large pessimistic safety margins to mitigate increased variability, however, they incur large power and performance loss as the combination of worst cases occurs very rarely. In-situ monitoring of timing failures provides an opportunity to dynamically tune safety margins in proportion to on-chip variability that can significantly minimize power and performance losses. We demonstrated by simulations two delay sensor designs to detect timing failures in advance that can be coupled with different compensation techniques such as voltage scaling, body biasing, or frequency scaling to avoid actual timing failures. Our simulation results using 45 nm and 32 nm technology BSIM4 models indicate significant reduction in total power consumption under temperature and statistical variations. Future work involves using dual sensing to avoid useless voltage scaling that incurs a speed loss. SRAM cache is the first victim of increased process variations that requires handcrafted design to meet area, power, and performance requirements. We have proposed novel 6 transistors (6T), 7 transistors (7T), and 8 transistors (8T)-SRAM cells that enable variability tolerant and low-power SRAM cache designs. Increased sense-amplifier offset voltage due to device mismatch arising from high variability increases delay and power consumption of SRAM design. We have proposed two novel design techniques to reduce offset voltage dependent delays providing a high speed low-power SRAM design. Increasing leakage currents in nano-CMOS technologies pose a major challenge to a low-power reliable design. We have investigated novel segmented supply voltage architecture to reduce leakage power of the SRAM caches since they occupy bulk of the total chip area and power. Future work involves developing leakage reduction methods for the combination logic designs including SRAM peripherals.
36
Schwarz, Cornelia. "Propriétés optomécaniques, vibrationelles et thermiques de membranes de graphène suspendues." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY024/document.
Full textAbstract:
Le but de la Nano- Opto- Mécanique et Electronic à base de graphène est d'utiliser des membranes de graphène en suspension comme blocs de construction pour aborder le couplage entre l'optique, la mécanique et l'électronique dans ce nouveau matériau. Avec un module d'Young similaire à celui du diamant (1 TPA), le graphène est une membrane extrêmement rigide, légère et mince (epaaisseur de seulement un atome) qui peut supporter son propre poids sans effondrement ou la rupture lorsqu'il est suspendu. Ces membranes, intégrées dans des dispositifs mécaniques, peuvent être actionnés à partir de DC jusqu'à des fréquences de vibration mécaniques très élevées (GHz). En outre, le graphène est un gaz d'électrons 2D exposé pour lequel une porte électrostatique tunes considérablement la densité de porteurs de charge et ses propriétés optiques. Last but not least, il offre une architecture unique pour effectuer la fonctionnalisation physico-chimiques et obtenir des matériaux hybrides combinant les propriétés particulières des espèces chimisorbées avec ceux du graphèneThe aim of the Graphene Nano- Opto- Mechanics and Electronics is to use suspended graphene membranes as building blocks to address the coupling of optics, mechanics and electronics in this novel material. With a Young modulus similar to that of diamond (1 TPa), graphene is an extremely stiff, light and atomically thin membrane that can withstand its own weight without collapsing or breaking when suspended. Such membranes, integrated as mechanical devices, can be actuated from DC up to very high mechanical vibration frequencies (GHz). Moreover, graphene is an exposed 2D electron gas for which an electrostatic gate dramatically tunes the charge carrier density and its optical properties. Last but not least, it provides a unique architecture to perform physico-chemical functionalization and obtain hybrid materials combining the peculiar properties of adsorbed and chemisorbed species with the graphene ones
37
Martin, Christopher. "Development of a bioelectric nerve conduit using solenoid technology, and nano fabrication." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/5278/.
Full textAbstract:
Peripheral nerve repair outcomes have lagged behind comparable surgical techniques for many decades. A number of advanced approaches have been adopted over the last ten years. In particular the application of electrical stimulation during a repair is of great interest. It is clear that electrical stimulation of regenerating nerve tissue has a great many effects and can improve functional outcomes for patients. This work has focused on developing systems capable of applying accurate electric fields on the microscale within a biodegradable conduit, powered wirelessly. Experiments were conducted in vitro with a view to making progress towards an in vivo implementation. Electrical stimulation was applied to regenerating sensory neurons in vitro, from a rat dorsal root ganglion. Mechanical guidance cues aligned neurons towards different microelectrode configurations in order to record the effect of applied electrical stimulation. This was performed using custom stimulation modules. SU-8 microgrooves and Ti/Au electrodes acted as mechanical and electrical cues respectively. This method was employed to great effect, identifying the effect of a number of electrical stimulation parameters. This led to a stimulation protocol featuring a 1:4 duty cycle, 20 mV amplitude, 100 Hz sinusoidal signal. This produced a number of interesting effects, including neuronal turning and a barrier formation. These results, demonstrated at the cellular level using a custom device and an autonomous stimulation system illustrates progress towards an optimised electrical stimulation waveform for neuronal growth control. A novel transfer printing process was developed to produce patterned gold films on the biodegradable polymer, polycaprolactone. Patterned Au, 400 nm thick, was transferred to a sheet of the polymer, producing a 15 turn, spiral inductor. The inductor was then electroplated to a thickness of 30 μm and wire-bonded. Power and data were transferred wirelessly to the receiver circuit. Receiver circuits, connected to stimulation test modules in planar form, delivered electrical stimulation waveforms to regenerating sensory neurons on polycaprolactone. This stimulation resulted in confinement of the cells between two pairs of electrodes, demonstrating the efficacy of the novel receiver circuits. This was achieved with four electrodes in a twin-barrier configuration. These results illustrate progress towards implantation in vivo, using remotely powered electronics to guide regenerating neurons to their targets with microelectrodes. Sensing cell growth through changes in electrical impedance is a well-documented technique. A receiver inductor has been connected to caco-2 cells in culture. Power was transmitted to the receiver inductor through an inductive link. Changes in the cell-monolayer have been detected at the transmitter output circuit, showing that the impedance changes are of sufficient magnitude to be reflected to the transmitter. Trypsin or EDTA were added to confluent layers of caco-2 cells, detaching them from the surface of the microchannel electrode array. This detachment was seen at the transmitter in the form of transient voltage changes. Data was acquired in using Labview programming and PXI hardware systems. This work illustrates progress towards biodegradable, passive cell sensing inspired by radio frequency identification technology, and electric cell impedance sensing.
38
Yao, Peng. "Developing three-dimensional lithography and chemical lithography for applications on micro/nano photonics and electronics." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 206 p, 2007. http://proquest.umi.com/pqdweb?did=1397913021&sid=11&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full text
39
Rezaee, Amirabbas, and amirabbas rezaee@rmit edu au. "Phase-Periodic Quantum Structures and Perturbed Potential Wells." RMIT University. Electrical and Computer Engineering, 2009. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20091218.160522.
Full textAbstract:
The restrictions of micro-scale systems are approaching rapidly. In anticipation of this development, nano-scale electronics has become the focus of many researchers and engineers in academia and industry since early 1990s. The basic building blocks of modern integrated circuits have been diodes and transistors with their current-voltage I-V characteristics being of prime significance for the design of complex signal processing and shaping devices and systems. Classical and semi-classical physical principles are no longer powerful enough or even valid to describe the phenomena involved. The application of rich and powerful concepts in quantum theory has become indispensable. These facts have been influential in undertaking this research project. This research is built upon the determination of the Eigenpairs of one and two dimensional positive differential operators with periodic boundary conditions. The Schrödinger equation was solved for positive operators in both one and two dimensions. Fourier series were used to express the derivatives as the summation of Fourier terms. This led to a novel approach for the calculation of the eigenmodels of a perturbed potential well. The perturbation can be done via an electric field applied to the potential well. The research in this thesis includes a thorough understanding of quantum mechanics fundamentals, mastering of different approximation techniques such as the variational technique and results that have been generated and published using the novel techniques.
40
Heath, Robert M. "Nano-optical studies of superconducting nanowire devices for single-photon detection." Thesis, University of Glasgow, 2015. http://theses.gla.ac.uk/6132/.
Full textAbstract:
Superconducting nanowire single photon detectors (SNSPDs) are a rapidly maturing detector technology that offer superior performance relative to competing infrared photon counting technologies. The original experimental work presented here explores three novel methods of improving and analysing detector characteristics, employing low-temperature piezoelectric motors at temperatures below 4 K in a closed-cycle cryostat. Utilizing the low-temperature piezoelectric nanopositioners in tandem with a miniature confocal microscope, this work specifically shows a spatially-separable parallel-wire SNSPD demonstrating one- and two-pixel photon discrimination, with the detector responding more quickly when triggering two pixels. The work demonstrates nanoantenna-coupled SNSPDs, which are simulated, designed, and tested using the same nano-optical setup. In these an increased local absorption into the nanowire is seen at the antennas' resonant wavelengths, enhancing the efficiency of the detector by up to 130 %. Finally, a modified optical setup using a distributed Bragg reflector fibre in place of the microscope to form a tunable cavity around two configurations of SNSPD is demonstrated, improving absorption of the incident light into the nanowire across the whole active area. For these, enhancement in the system detection efficiency of up to 40 % is seen.
41
Amakubo, Suguru Frederick. "Carbon electronics : nano-carbons for the development of radiation sensors, image intensifiers and medical sensors." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/10024912/.
Full textAbstract:
Carbon nano-materials, both in sp2 (graphene like) and sp3 (diamond) con- figurations are renowned for their unmatched novel properties. In particular, its extremely high electrical conductivity, radiation hardness and electron amplification are widely coveted. This investigation aims to capitalise on the above by developing blood pressure sensors, radiation detectors and signal amplifiers from the said carbon nano-materials. Namely, carbon nanotubes (sp2 carbon) were integrated into a polymer host to form a composite. Where it has been found that by altering the surface functionalisations of carbon nanotubes (non-functionalised, -OH and -COOH) the electrical resistance of the composite could vary drastically as much as 1012Ω to 107Ω. This brings potential benefits in reduced production costs, reduced environmental damage and wider technological adoption of carbon composite based devices. Carbon nanotubes were then encased in a soft and biocompatible host, polydimethylsiloxane (PDMS), in order to fabricate an in vivo blood pressure sensor, exploiting its piezo-resistivity. Results have shown a successful and adequate degree of piezo-resistivity (109Ω to 106Ω for 2D and 4kΩ to 750kΩ for 3D compression) at the desired size-scale of 200μm and 4mm respectively. This is a size equivalent to that of the diameter of blood vessels in question. However, further investigation into re-miniaturisation is recommended for future works. Diamond (sp3 carbon), on the other hand, was used as a longlasting solution to neutron detection for a Trident nuclear submarine, HMS Artful. The investigation entailed a three-phase process of: α-particle detection, LiF conversion layer addition and neutron detection. Results has shown clear signs of α-particle and neutron detection with a device efficiency of 32.3% and 48.3% respectively, as well as γ-ray transparency and sufficient Q-factor between the signal peak and detection peak. Diamond was also used as a signal amplifier that has application as an image intensifier for night-vision goggles where it was found thatby altering the surface functionalisation of nano-diamonds (H, O and LiO) one could enhance or suppress the secondary electron emission effect. Additionally, it was found that the electrical gain from the said secondary electron emission has a strong dependence on the crystal structure of the diamond layer and in turn its growth conditions. Most notably, LiO functional group was found to be more resilient towards higher temperatures (800oC) and electron bombardments but fell short in the amount of electrical gain it generated in comparison to conventional functionalisations such as H. However, the X-ray photoelectron spectroscopy (XPS) results suggest that this may be due to the lack of LiO coverage and upon further investigation, LiO may potentially bode better if not surpass the gain performance of H.
42
Maturi, Mirko <1993>. "Advanced Functional Organic-Inorganic Hybrid (Nano)Materials: from Theranostics to Organic Electronics and Additive Manufacturing." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amsdottorato.unibo.it/9739/1/Maturi_Mirko_tesi.pdf.
Full textAbstract:
This work is going to show the activities performed in the frame of my PhD studies at the University of Bologna, under the supervision of Prof. Mauro Comes Franchini, at the Department of Industrial Chemistry “Toso Montanari”. The main topic of this dissertation will be the study of organic-inorganic hybrid nanostructures and materials for advanced applications in different fields of materials technology and development such as theranostics, organic electronics and additive manufacturing, also known as 3D printing.
This work is therefore divided into three chapters, that recall the fundamentals of each subject and to recap the state-of-the-art of scientific research around each topic. In each chapter, the published works and preliminary results obtained during my PhD career will be discussed in detail.
43
Mahmood, Tamara. "Micro and nano analysis of a novel polymeric bioresorbable scaffold and its drug release." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/51775/.
Full textAbstract:
The composition of the top-most molecular layers of solid materials is of great importance in the understanding of many technologically important processes. This is especially so, for example for devices exposed to the in vivo environment of our bodies especially if long term functionality is required. Cardiovascular stents or scaffolds are a biomedical implant that must maintain structural and functional integrity for periods of months to achieve their therapeutic goal. In this work, the fully polymeric drug-eluting bioresorbable scaffold, ArterioSorbTM is characterised, paying particular attention to surface and near surface properties. The introduction of cardiovascular stents has considerably enhanced the potential of surgical intervention via angioplasty. Biomaterials used for implants may be metallic, ceramic, polymeric or composite. A new generation of drug eluting stent are now emerging, such as the Poly(L-lactide) (PLLA) based fully biodegradable stents studied here, that have the potential to increase the therapeutic potential of this approach even further. PLLA is a bioabsorbable semi-crystalline polymer that possesses a low elongation and high tensile strength, which makes it appropriate for this medical application. Using a spray-coating method a sirolimus/PDLLA layer was coated onto the surface of a bioresorbable PLLA scaffold by Arterius Ltd. The aim of this thesis is the study of the drug distribution and physiochemical properties of the biomedical device and to relate this information to likely drug release mechanisms under physiological conditions. Complementary surface and near-surface analysis techniques including scanning electron microscopy (SEM), atomic force microscopy (AFM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS) and confocal Raman imaging (CRM) have been used to assess structure, composition and their relation to drug release. Primarily, this work was carried out on a series of extruded and orientated (die-drawn) PLLA tubing before considering the actual bioresorbable medical device (uncoated, coated expanded and crimped scaffolds). ToF-SIMS has been used to confirm the chemical homogeneity of the PLLA coating and provide evidence of some minor surface elemental contamination likely due to transfer of fluorine from packaging/sample handling. The drug (sirolimus) was clearly observed and mapped at the microscale at the surface and in the bulk of the scaffold coating. In addition, the physical properties of these materials were investigated using nano and micro thermal analysis. The percentage of crystallinity of the PLLA materials was studied using Differential Scanning Calorimetry (DSC). Attenuated total reflection infrared (ATR-IR) helped in assessing the structure of PLLA. Factors including the manufacturing process used have been shown to have an effect on the materials. The degradation in vitro has been shown to be influenced by the molecular weight of the polymer and the concentration of the drug. This thesis is organised into six chapters. Chapter 1 provides an introduction to the technical requirements needed for bioresorbable stent and outlines the literature review and research context for the development of the scaffold, including materials used for the manufacturing of the scaffold, spray coating method and laser cutting techniques. Chapter 2 describes the instrumentation and methodology used for characterising such medical device as well as a description of laser cutting used in manufacture. Chapter 3 presents a feasibility study on the extruded and oriented tubing. Chapter 4 describes the characterisation of the drug distribution in the drug/polymer matrix. Chapter 5 provides a detailed characterisation of the in vitro degradation of sirolimus/PDLLA coating layer revealing the release kinetics of the device. Finally, Chapter 6 gathers information learnt throughout this thesis and explored future directions to improve release and performance of such a device.
44
Wang, Qi. "The effect of nano size fillers on electrical performance of epoxy resin." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/340660/.
Full textAbstract:
Epoxy resin is widely used in high voltage apparatus as insulation due to its excellent mechanical, electrical and chemical properties. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite materials with enhanced electrical, thermal and mechanical properties. The project aims to improve the overall electrical performance by adding nanoparticles into epoxy resin. In the present thesis a detailed study on dielectric permittivity, AC breakdown strength and space charge behaviour of epoxy resin/nanocomposites with nano-fillers of SiO2 and Al2O3 has been carried out. The epoxy resin/nanocomposite thin film samples were prepared and tests were carried out to measure their dielectric permittivity and tan delta value in frequency range of 1Hz- 1MHz. The space charge behaviours were also observed by using the pulse electroacoustic (PEA) technique. The influence of filler type, filler size and filler concentration on nanocomposites ac breakdown strength were also examined. In addition, traditional epoxy resin microcomposites were also prepared and tested and the results were compared with those obtained from epoxy resin/nanocomposites. The present results indicate that the presence of nano-sized fillers enhances the insulation properties of the epoxy resin and the dielectric properties are strongly influenced by the interfacial region between epoxy and nano particles. It is the key factor that affects the electrical performance of epoxy nanocomposites. The multi core model has been applied to explain the effects of such interfacial region on the electrical performance epoxy nanocomposites. A new phenomenon of space charge accumulation at higher nano size filler loading concentration has been observed at a filler loading concentration above 3wt%. This phenomenon is a result of the formation of electrical double layer surrounding the nano particles. A comparison study between epoxy nanocomposites loaded with both surface treated and non-surface treated nano particles has also been carried out. The results indicate that nano particle dispersion rate is an important factor in determine the electrical performance epoxy nanocomposites. Surface functionalisation on nano size fillers by using silane as a coupling agent could help avoiding the formation of large agglomerations resulting in better insulating performance. In addition, it has also been found that the presence of water inside epoxy nanocomposites also leads to the reduction in dielectric properties due to the formation of water layers surrounding the nano particles. Those water layers could act as a conductive path to help charge carriers travelling through the bulk of the materials.
45
Bricchi, Erica. "Femtosecond laser micro-machining and consequent self-assembled nano-structures in transparent materials." Thesis, University of Southampton, 2005. https://eprints.soton.ac.uk/30234/.
Full textAbstract:
In this thesis we have reported novel developments in the field of femtosecond laser micro-machining within the bulk of transparent materials. Thanks to its unique properties, the femtosecond laser writing technique offers the potential for realizing three-dimensional multi-component photonic devices, fabricated in a single step and in a variety of transparent materials. When we began to research in this field, there had been no studies conducted on the ability of femtosecond lasers to fabricate diffractive optical components in the bulk of a dielectric material. These are necessary components for the realization of monolithic optical devices. Our work led to the first demonstration of femtosecond directly written diffractive optic devices (Fresnel zone plates) embedded in a silica substrate. Both the focusing properties and efficiencies of the devices compared well with the theoretical values.
46
Ip, Brian Kau 1962. "Design trade-off study for delta-doped Si/SiGe heterostructure MOSFET's: The potential nano-MOSFET's." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282544.
Full textAbstract:
A design trade-off study for n-channel δ-doped Si/SiGe heterojunction MOSFET's has been performed using a combination of numerical simulation and analysis. The design parameters unique to the δ-doped Si/SiGe heterostructure MOSFET's have been studied in terms of their effects on short-channel immunity, off-state leakage and on-state current. Our study shows that cap and channel layer must always be made as thin as possible to reduce the separation of the mobile charge centroid from the surface, in which case better short-channel immunity, better leakage and driving ability will result. On the other hand, the setback layer thickness, potential well depth and δ-doping dose are found to be trade-off parameters. Design windows that based on the trade-off parameters were constructed to obtained optimal designs for 0.2. μm channel length and 1.5 V supply voltage, and 0.1 μm channel length and 1 V supply voltage δ-doped Si/SiGe heterojunction MOSFET's. When compared to similarly configured conventional bulk MOSFET's, the 0.2 μm-1.5V design has approximately the same characteristics while the 0.1 μm-1V design has a 25% advantage in short-channel immunity. The δ-doped Si/SiGe heterojunction MOSFET is then redesigned by removing the cap layer, which results in a smaller effective oxide thickness but lower low-field mobility. The new structure is found to produce a 0.1μm-1V design that has improvement of 22% in on-state current, 54% in off-state leakage and 17% in short-channel immunity over the structure with the cap layer. We further are successful in producing a 70nm-1.2V design with excellent characteristics that cannot be reached by conventional MOSFET's. We conclude that the δ-doped Si/SiGe heterojunction MOSFET's without a cap layer have a high potential as the future high-performance transistors that can deliver high speed, high density and low power applications.
47
Reid, David T. "Large-scale simulations of intrinsic parameter fluctuations in nano-scale MOSFETs." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/1960/.
Full textAbstract:
Intrinsic parameter fluctuations have become a serious obstacle to the continued scaling of MOSFET devices, particularly in the sub-100 nm regime. The increase in intrinsic parameter fluctuations means that simulations on a statistical scale are necessary to capture device parameter distributions. In this work, large-scale simulations of samples of 100,000s of devices are carried out in order to accurately characterise statistical variability of the threshold voltage in a real 35 nm MOSFET. Simulations were performed for the two dominant sources of statistical variability – random discrete dopants (RDD) and line edge roughness (LER). In total ∼400,000 devices have been simulated, taking approximately 500,000 CPU hours (60 CPU years). The results reveal the true shape of the distribution of threshold voltage, which is shown to be positively skewed for random dopants and negatively skewed for line edge roughness. Through further statistical analysis and data mining, techniques for reconstructing the distributions of the threshold voltage are developed. By using these techniques, methods are demonstrated that allow statistical enhancement of random dopant and line edge roughness simulations, thereby reducing the computational expense necessary to accurately characterise their effects. The accuracy of these techniques is analysed and they are further verified against scaled and alternative device architectures. The combined effects of RDD and LER are also investigated and it is demonstrated that the statistical combination of the individual RDD and LER-induced distributions of threshold voltage closely matches that obtained from simulations. By applying the statistical enhancement techniques developed for RDD and LER, it is shown that the computational cost of characterising their effects can be reduced by 1–2 orders of magnitude.
48
Bukhori, Muhammad Faiz. "Simulation of charge-trapping in nano-scale MOSFETs in the presence of random-dopants-induced variability." Thesis, University of Glasgow, 2011. http://theses.gla.ac.uk/2810/.
Full textAbstract:
The growing variability of electrical characteristics is a major issue associated with continuous downscaling of contemporary bulk MOSFETs. In addition, the operating conditions brought about by these same scaling trends have pushed MOSFET degradation mechanisms such as Bias Temperature Instability (BTI) to the forefront as a critical reliability threat. This thesis investigates the impact of this ageing phenomena, in conjunction with device variability, on key MOSFET electrical parameters. A three-dimensional drift-diffusion approximation is adopted as the simulation approach in this work, with random dopant fluctuations—the dominant source of statistical variability—included in the simulations. The testbed device is a realistic 35 nm physical gate length n-channel conventional bulk MOSFET. 1000 microscopically different implementations of the transistor are simulated and subjected to charge-trapping at the oxide interface. The statistical simulations reveal relatively rare but very large threshold voltage shifts, with magnitudes over 3 times than that predicted by the conventional theoretical approach. The physical origin of this effect is investigated in terms of the electrostatic influences of the random dopants and trapped charges on the channel electron concentration. Simulations with progressively increased trapped charge densities—emulating the characteristic condition of BTI degradation—result in further variability of the threshold voltage distribution. Weak correlations of the order of 10-2 are found between the pre-degradation threshold voltage and post-degradation threshold voltage shift distributions. The importance of accounting for random dopant fluctuations in the simulations is emphasised in order to obtain qualitative agreement between simulation results and published experimental measurements. Finally, the information gained from these device-level physical simulations is integrated into statistical compact models, making the information available to circuit designers.
49
Zhang, Tan Tan. "Sub-nano-watt subthreshold-biased source-follower-based LPF for biopotential signal acquisition systems." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2182899.
Full text
50
Zhao, Wei. "Flexible Transparent Electrically Conductive Polymer Films for Future Electronics." University of Akron / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=akron1297888558.
Full text