Дисертації з теми "Carbon Doping in GaN"
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Ciarkowski, Timothy A. "Low Impurity Content GaN Prepared via OMVPE for Use in Power Electronic Devices: Connection Between Growth Rate, Ammonia Flow, and Impurity Incorporation." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/94551.
Повний текст джерелаDoctor of Philosophy
GaN is a compound semiconductor which has the potential to revolutionize the high power electronics industry, enabling new applications and energy savings due to its inherent material properties. However, material quality and purity requires improvement. This improvement can be accomplished by reducing contamination and growing under extreme conditions. Newly available bulk substrates with low defects allow for better study of material properties. In addition, very thick films can be grown without cracking on these substrates due to exact lattice and thermal expansion coefficient match. Through chemical and electrical measurements, this work aims to find optimal growth conditions for high purity GaN without a severe impact on growth rate, which is an important factor from an industry standpoint. The proposed thicknesses of these devices are on the order of one hundred microns and requires tight control of impurities.
Ashourirad, Babak. "HETEROATOM-DOPED NANOPOROUS CARBONS: SYNTHESIS, CHARACTERIZATION AND APPLICATION TO GAS STORAGE AND SEPARATION." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/4062.
Повний текст джерелаKleinsorge, Britta Yvonne. "Doping of amorphous carbon." Thesis, University of Cambridge, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621744.
Повний текст джерелаRIBEIRO, MARIO LUIS PIRES GONCALVES. "CARBON DOPING IN INAIAS EPITAXIAL LAYERS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2002. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=2651@1.
Повний текст джерелаERICSSON DO BRASIL
É reconhecido o potencial de usar carbono como um dopante tipo p em InAlAs devido a obtenção de elevados níveis de dopagem [1,2]. Entretanto, níveis elevados de dopagem só são alcançados em baixas temperaturas de crescimento (Tg inferiores a 600°C). Nessas temperaturas, as camadas crescidas apresentam qualidade ótica inferior quando comparadas com camadas crescidas em temperaturas mais altas, o que é prejudicial para dispositivos de optoeletrônica. Neste trabalho, é apresentada uma investigação sistemática das propriedades de transporte e óticas em camadas de InAlAs dopadas com carbono para diferentes temperaturas de crescimento. É observado que quanto mais baixa for a Tg maior será a incorporação de carbono e maior a atividade elétrica. Este resultado indica que o carbono é incorporado de diversas maneiras, bem como um aceitador raso. O carbono também pode ser incorporado como um doador raso, pois é um dopante anfotérico. Entretanto, este fato, não é suficiente para explicar os resultados de transporte. A diferença entre a concentração Hall e a concentração CV indica a incorporação de doadores profundos. Provavelmente, o carbono participa na formação desses doadores profundos, uma vez que a concentração de doador profundo varia linearmente com a densidade atômica de carbono, determinada pela técnica SIMS. Por outro lado, centros não radiativos são mais facilmente incorporados em baixas Tg e a eficiência da fotoluminescência é reduzida. Essa degradação da fotoluminescência é independente da concentração de carbono, consequentemente, pode-se concluir que essa redução na eficiência da fotoluminescência não está associada à presença de doadores profundos. Com a finalidade de obter um incremento na atividade elétrica do carbono e melhoria na qualidade ótica das camadas, as amostras foram submetidas a tratamentos térmicos. Os tratamentos térmicos aumentaram a concentração de buracos mas não influenciaram na densidade de doadores profundos ou na qualidade ótica das camadas. Para a utilização de InAlAs dopado com carbono em dispositivos, deve-se obter simultaneamente uma boa qualidade ótica e elevada atividade elétrica das camadas.Então, deve-se identificar o doador profundo, que está associado ao carbono, com o objetivo de reduzí-lo ou eliminá-lo e consequentemente, obter um incremento na atividade elétrica das camadas. Desta forma as camadas podem ser crescidas a temperaturas mais altas adequadas para uma emissão de fotoluminescência eficiente. Cálculos teóricos são apresentados de modo a ajudar essa identificação. Outra possibilidade é usar diferentes fontes de arsina em que as moléculas se dissociem em temperaturas mais baixas.
The potential of using carbon as a p-type dopant for InAlAs has already been recognized due to the achievable high hole concentration [1,2]. However, high doping levels are reached only for low growth teperatures (Tg below 600°C). These temperatures produce layers with poor optical quality as compared to those grown at higher temperatures, which can be detrimental for optoeletronic device. In this work we present crystal, transport and optical properties of such layers grown at different temperatures. We find that the lower Tg, the more efficient the carbon incorporation and its electrical activity are. This result indicates that carbon is incorporated in forms different from a shallow acceptor, as well. Carbon can also be incorporated as a shallow donor since it is an amphoteric dopant. However, this alone does not explain the transport results. The difference between the net free charge density determined from capacitance measurements indicates that a deep donor is also incorporated. Carbon most likely participates in the deep donor formation since the inferred deep donor concentration varies linearly with the carbon atomic density measured by SIMS. On the other hand, non- radiative deep levels are more efficiently incorporated as Tg is reduced degrading the photoluminescence characteristics. Such degration is independent of the carbon doping. Therefore, one concludes that the decrease in the photoluminescence efficiency cannot be related to the presence of the deep donor mentioned in the previous paragraph. To further probe the carbon electrical activity and its effect on the optical properties of the layers, the samples have been subjected to a heat-treatment. Annealing the samples increases the hole concentration, but neither affects the deep donor density nor improves the layers optical quality. In order to use carbon doped InAlAs in devices which simultaneously require good optical quality and high electrical activity of the layers, one should identify the deep donor involving carbon in order to try to reduce its concentration or even eliminate it, consequently improving the electrical activity of the layers. In such a way the layers can be grown at higher temperatures, adequate for an efficient photoluminescence emission. Theoretical calculations are being carried out to help with such identification. Another possibility is to use other arsine sources which crack at lower temperatures.
Khromov, Sergey. "Doping effects on the structural and optical properties of GaN." Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-100760.
Повний текст джерела彭澤厚 and Chak-hau Pang. "A study of Mg doping in GaN during molecular beam epitaxy." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226619.
Повний текст джерелаPang, Chak-hau. "A study of Mg doping in GaN during molecular beam epitaxy /." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B25059075.
Повний текст джерелаAlluqmani, Saleh Marzoq B. "Growth and doping of carbon nanotubes and graphene." Thesis, Durham University, 2015. http://etheses.dur.ac.uk/10949/.
Повний текст джерелаFrancis, Smita. "Optimisation of doping profiles for mm-wave GaAs and GaN gunn diodes." Thesis, Cape Peninsula University of Technology, 2017. http://hdl.handle.net/20.500.11838/2568.
Повний текст джерелаGunn diodes play a prominent role in the development of low-cost and reliable solid-state oscillators for diverse applications, such as in the military, security, automotive and consumer electronics industries. The primary focus of the research presented here is the optimisation of GaAs and GaN Gunn diodes for mm-wave operations, through rigorous Monte Carlo particle simulations. A novel, empirical technique to determine the upper operational frequency limit of devices based on the transferred electron mechanism is presented. This method exploits the hysteresis of the dynamic velocity-field curves of semiconductors to establish the upper frequency limit of the transferred electron mechanism in bulk material that supports this mechanism. The method can be applied to any bulk material exhibiting negative differential resistance. The simulations show that the upper frequency limits of the fundamental mode of operation for GaAs Gunn diodes are between 80 GHz and 100 GHz, and for GaN Gunn diodes between 250 GHz and 300 GHz, depending on the operating conditions. These results, based on the simulated bulk material characteristics, are confirmed by the simulated mm-wave performance of the GaAs and GaN Gunn devices. GaAs diodes are shown to exhibit a fundamental frequency limit of 90 GHz, but with harmonic power available up to 186_GHz. Simulated GaN diodes are capable of generating appreciable output power at operational frequencies up to 250 GHz in the fundamental mode, with harmonic output power available up to 525 GHz. The research furthermore establishes optimised doping profiles for two-domain GaAs Gunn diodes and single- and two-domain GaN Gunn diodes. The relevant design parameters that have been optimised, are the dimensions and doping profile of the transit regions, the width of the doping notches and buffer region (for two-domain devices), and the bias voltage. In the case of GaAs diodes, hot electron injection has also been implemented to improve the efficiency and output power of the devices. Multi-domain operation has been explored for both GaAs and GaN devices and found to be an effective way of increasing the output power. However, it is the opinion of the author that a maximum number of two domains is feasible for both GaAs and GaN diodes due to the significant increase in thermal heating associated with an increase in the number of transit regions. It has also been found that increasing the doping concentration of the transit region exponentially over the last 25% towards the anode by a factor of 1.5 above the nominal doping level enhances the output power of the diodes.
Khromov, Sergey. "The Effect of Mg Doping on Optical and Structural Properties of GaN." Licentiate thesis, Linköpings universitet, Tunnfilmsfysik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-75428.
Повний текст джерелаFang, Zhihua. "N and p-type doping of GaN nanowires : from growth to electrical properties." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY007/document.
Повний текст джерелаIII-nitride nanostructures have been attracting increasing attention due to their peculiar properties and potential device applications as lighting LEDs. The control and evaluation of the doping in the nanostructures is a crucial, yet a challenging issue. This thesis advances the field by exploring the n and p type doping process of GaN nanowires (NWs) grown by molecular beam epitaxy (MBE). In particular, their electrical properties have been revealed through a multi-technique approach at the single NW level.Firstly, the structural and electrical properties of a series of Si-doped (n-type) GaN NWs have been studied. High resolution energy dispersive X-ray spectroscopy measurements on single NWs have illustrated the achievement of a higher Si incorporation in NWs than in epilayers, and Si segregation at the edge of the NW with the highest doping. Furthermore, direct transport measurements (four probes measurements from 300 K down to 5 K) on single NWs have shown a controlled doping with resistivity from 10^2 to 10^-3 Ω.cm, and a carrier concentration from 10^17 to 10^20 cm-3. Field effect transistor measurements have evidenced the n-type nature and a high electron mobility of the non-intentionally doped NWs.Secondly, the growth conditions of Mg-doped (p-type) and axial GaN p-n junction NWs have been determined to achieve significant Mg incorporation. Furthermore, the electrical properties of the axial GaN p-n junction NWs, dispersed on SiO2 and contacted by ITO, have been studied using electron beam induced current (EBIC) technique. EBIC technique revealed the location of the p-n junction and clearly demonstrated its operation under reverse and forward polarization. Moreover, EBIC showed highly resistive p-GaN in accordance with the difficulties to perform direct transport measurements on p-GaN NWs.This original study provides a nanoscale description of the electrical and doping properties of the GaN NWs, facilitating the fabrication of the future GaN nanostructures based devices
Sanwick, Alexis. "Heteroatom-Doped Chemical Vapor Deposition Carbon Ultramicroelectrodes." Digital Commons @ East Tennessee State University, 2020. https://dc.etsu.edu/honors/592.
Повний текст джерелаKendrick, Chito Edsel. "Revisiting Nitride Semiconductors: Epilayers, p-Type Doping and Nanowires." Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/2108.
Повний текст джерелаLiang, Meng Suan. "Carbon doping in GaAs, AlGaAs, InGaAs and distributed Bragg reflectors." Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399255.
Повний текст джерелаAnwar, Abdul Waheed. "Investigation of doping and photoexcitation in carbon nanotubes using Raman spectroscopy." Toulouse 3, 2011. http://thesesups.ups-tlse.fr/1156/.
Повний текст джерелаRaman spectroscopy is a non-invasive characterization technique suitable for the study of carbon nanotubes. Differences in the spectral shift of the Raman D and G bands are observed when heating carbon nanotubes through intense photon irradiation and by varying the temperature in a thermostat. These spectral changes in D mode are attributed to the variation of the electronic band structure by excitons creation. The investigation of the influence of doping and photoexcitation on the Raman G and D band of carbon nanotubes show that Raman spectroscopy can be used as a diagnostic tool. The spectral bands broaden and up shifts for nitrogen doped multi walled carbon nanotubes (MWCNT). The up shift for sulphuric acid doped double wall carbon nanotubes (DWCNT) synthesized from catalytic chemical vapor deposition method (CCVD) is attributed to charge transfer and strain in the lattice. We have combined sulphuric acid doping and high pressure Raman spectroscopy to investigate the properties of DWCNT. The DWCNT doped with different concentrations of sulphuric acid are explored under high pressure suggesting an effect of the molecular ordering around carbon nanotubes at higher acid concentrations. Raman spectra of individual double wall carbon nanotubes on silica show a splitting of the G band due to contributions of the inner and outer tube when using a excitation energy in resonance with the inner metallic tube and outer semiconducting tube. The spectral line widths are comparable to what has been observed for individual single wall carbon nanotubes (SWCNT) or graphene. Increased laser power shifts the G band of the outer tube to higher energies and modifies its line shape
Sojoudi, Hossein. "The synthesis, doping, and characterization of graphene films." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/50125.
Повний текст джерелаPinto, Hugo Manuel. "Defects and dopants in carbon related materials." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3601.
Повний текст джерелаVillalpando, Paéz Federico. "Effects of doping single and double walled carbon nanotubes with nitrogen and boron." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36215.
Повний текст джерелаIncludes bibliographical references (p. 135-143).
Controlling the diameter and chirality of carbon nanotubes to fine tune their electronic band gap will no longer be enough to satisfy the growing list of characteristics that future carbon nanotube applications are starting to require. Controlling their band gap, wall reactivity and mechanical properties is imperative to make them functional. The solution to these challenges is likely to lie in smart defect engineering. Defects of every kind can induce significant changes on the intrinsic properties of carbon nanotubes. In this context, this thesis analyzes the effects of doping single and double walled carbon nanotubes with nitrogen and boron. We describe the synthesis of N-doped single-walled carbon nanotubes (N-SWNTs), that agglomerate in bundles and form long strands (<10cm), via the thermal decomposition of ferrocene/ethanol/benzylamine (FEB) solutions in an Ar atmosphere at 950°C. Using Raman spectroscopy, we noted that as the N content is increased in the starting FEB solution, the growth of large diameter tubes is inhibited. We observed that the relative electrical conductivity of the strands increases with increasing nitrogen concentration. Thermogravimetric analysis (TGA) showed novel features for highly doped tubes, that are related to chemical reactions on N sites.
(cont.) We also carried out resonance Raman studies of the coalescence process of double walled carbon nanotubes in conjunction with high resolution transmission electron microscope (HRTEM) experiments on the same samples, heat treated to a variety of temperatures and either undoped or Boron doped. As the heat treatment temperatures are increased (to 1300°C) a Raman mode related to carbon-carbon chains (w = 1855cm-1) is observed before DWNT coalescence occurs. These chains are expected to be 3-5 atoms long and they are established covalently between adjacent DWNTs. The sp carbon chains trigger nanotube coalescence via a zipper mechanism and the chains disappear once the tubes merge. Other features of the Raman spectra were analyzed as a function of heat treatment with special emphasis on the metallic or semiconducting nature of the layers constituting the DWNTs. DWNTs whose outer wall is metallic tend to interact more with the dopant and their outer tubes are the predominant contributors to the line shape of the G and G' bands.
(cont.) The metallic or semiconducting nature of the layers of the DWNTs does not affect their coalescence temperature. All the experiments and analysis presented in this thesis are the result of a collaborative effort between Professor Dresselhaus' group at MIT and its international collaborators, including Professor Endo's group at Shinshu University, Nagano, Japan, Professors Pimenta's and Jorio's group at the Federal University of Minas Gerais, Belo Horizonte, Brazil, and Professors M. and H. Terrones' group at IPICYT, San Luis Potosi, Mexico.
by Federico Villalpando Paéz.
S.M.
Chindanon, Kritsa. "Nitrogen doping in low temperature halo-carbon homoepitaxial growth of 4H-silicon carbide." Master's thesis, Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-07102008-045510.
Повний текст джерелаHopkin, Amy L. "Methane conversion over supported nickel catalysts : influence of gold doping, support material and preparation method." Thesis, Keele University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288499.
Повний текст джерелаEsmaeili, Mostafa. "The Effects of Nitrogen doping on Chemical, Optical and Electronic properties of Carbon Dots." Thesis, Griffith University, 2022. http://hdl.handle.net/10072/414280.
Повний текст джерелаThesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
Full Text
Mawudoku, Daniel, George Affadu_Danful, Caitlin Millsaps, and Gregory Bishop. "Immobilization of Electrocatalytically Active Gold Nanoparticles on Nitrogen-Doped Carbon Fiber Electrodes." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/asrf/2019/schedule/106.
Повний текст джерелаYe, Jianting. "Fabrication analysis and lithium doping in 4 Å carbon nanotubes in the channels of AlPO4̳-5 crystal /." View Abstract or Full-Text, 2002. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202002%20YE.
Повний текст джерелаOn t.p. "4̳" is subscript. Includes bibliographical references (leaves 84-86). Also available in electronic version. Access restricted to campus users.
Kuo, Ming-Tsun. "Field emission and annealing studies of n-type doped hydrogenated amorphous carbon films." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340300.
Повний текст джерелаWebb, Kimberly Faye. "Synthesis, blending, and doping of electrically conducting poly(3-undecylbithiophene) in supercritical carbon dioxide." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/10129.
Повний текст джерелаLardeau-Falcy, Aurélien. "Dopage de couches de GaN sur substrat silicium par implantation ionique." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY024/document.
Повний текст джерелаGaN-based devices and their alloys are increasingly present in our daily lives with the exponential development of light-emitting diodes (LEDs). Although the majority of commercial production is currently carried out on sapphire substrates, silicon, available in larger diameters and at a lower cost, is increasingly seen as the substrate of the future for the development of GaN technologies. The use of this substrate should also allow the development of the GaN power electronics market based on high electron mobility transistors (HEMTs) whose performances exceed the limits of silicon technologies. Nevertheless, in order to allow or facilitate the development of advanced devices, specific processes are necessary such as doping by ion implantation. The use of GaN raises new problems for these technological bricks.During this thesis we therefore sought to implement the ion implantation doping process of GaN and its study within the CEA-LETI while focusing mainly on p doping by Mg implantation. We have identified the main issues related to the intrinsic properties of the material (difficulty of p-doping, instability at high temperatures...) and the most promising solutions in the literature. We then sought to implement our own process by developing in-situ protective layers to allow high temperature annealing of the implanted layers. This enabled the study of the evolution kinetics of the implanted layers during "conventional" annealing (ramps < 10 °C/min, duration of several tens of minutes, T < 1100 °C) using photoluminescence (µ-PL) and X-ray diffraction (XRD) characterizations. We also evidenced a diffusion and aggregation effect at high temperature of the implanted Mg. We then sought to modify the implantation process (channeled implantation, co-implantation) to promote the integration of the dopant and limit the formation of defects. In parallel we evaluated the interest of secondary annealing (Rapid thermal annealing (RTA), laser annealing, microwave) in order to finalize the activation of the dopant. Finally we also set up an electrical characterization process for doped GaN layers in the laboratory
Zhong, Mingyu. "Doped GaN grown by Phase Shift Epitaxy, fabrication and characterization of GaN:Eu LED." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1384427470.
Повний текст джерелаIve, Tommy. "Growth and investigation of AlN/GaN and (Al,In)N/GaN based Bragg reflectors." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15395.
Повний текст джерелаWe study the synthesis of AlN/GaN and (Al,In)N/GaN Bragg reflectors. The structures were grown by plasma-assisted molecular beam epitaxy (MBE) on 6H-SiC(0001) substrates. In addition, we study the impact of Si-doping on the surface morphology and the structural and electrical properties of the AlN/GaN Bragg reflectors. Crack-free and high-reflectance (R>99%) Bragg reflectors were achieved with a stopband centered at 450 nm. The Si-doped structures exhibit ohmic I-V behavior in the entire measurement range. The specific series resistance is 2-4 mOhmcm2. The results of the (Al,In)N growth experiments are summarized in a phase diagram which clearly shows the optimum growth window for (Al,In)N.
Ajay, Akhil. "Nanofils de GaN/AlGaN pour les composants quantiques." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAY030/document.
Повний текст джерелаDue to its novel properties nanowires have emerged as promising building blocks for various advanced device applications. This work focuses on Intersubband (ISB) engineering of nanowires where we custom design GaN/(Al,Ga)N heterostructures to be inserted in a GaN nanowire to render it optically active in the infrared (IR) spectral region. ISB transitions refer to energy transitions between quantum confined levels in the conduction band of the nanostructure. All the structures analised in this thesis were synthesized by plasma-assisted molecular beam epitaxy.Precise control of high doping levels is crucial for ISB devices. Therefore, we explored Ge as an alternative dopant for GaN and AlGaN, to replace commonly-used Si. We grew Ge-doped GaN thin films with carrier concentrations of up to 6.7 × 1020 cm−3 at 300 K, well beyond the Mott density, and we obtained conductive Ge-doped AlxGa1-xN thin films with an Al mole fraction up to x = 0.66. In the case of GaN, the presence of Ge does not affect the growth kinetics or structural properties of the samples. However, in Ge doped AlxGa1-xN samples with x > 0.4 the formation of Ge rich clusters was observed, together with a drop in the carrier concentration.Then, we performed a comparative study of Si vs. Ge doping in GaN/AlN heterostructures for ISB devices in the short-wavelength IR range. We considered both planar and nanowire architectures with identical doping levels and well dimensions. Based on this study, we concluded that both Si and Ge are suitable dopants for the fabrication of GaN/AlN heterostructures for the study of ISB optoelectronic phenomena, both in planar and nanowire heterostructures. Within this study, we reported the first observation of ISB absorption in Ge-doped GaN/AlN quantum wells and in Si-doped GaN/AlN nanowire heterostructures. In the case of nanowires, we obtained a record ISB absorption linewidth in the order of 200 meV. However, this value is still larger than that observed in planar structures, due to the inhomogeneities associated to the self-assembled growth process.Trying to reduce the inhomogeneities while keeping the advantages of the nanowire geometry, we also presented a systematic analysis of ISB absorption in micro- and nanopillars resulting from top-down processing GaN/AlN planar heterostructures. We showed that, when the spacing of the pillar array is comparable to the probed wavelengths, photonic crystal resonances dominate the absorption spectra. However, when these resonances are at much shorter wavelengths than the ISB absorption, the absorption is clearly observed, without any degradation of its magnitude or linewidth.We also explore the possibility to extend this nanowire technology towards longer wavelengths, to absorb in the mid-wavelength IR region. Using GaN/AlN nanowire heterostructures, we varied the GaN well width from 1.5 to 5.7 nm, which led to a red shift of the ISB absorption from 1.4 to 3.4 µm. Replacing the AlN barriers by Al0.4Ga0.6N, the reduction of polarization led to a further red shift of the ISB transitions to 4.5-6.4 µm.The observation of ISB absorption in nanowire ensembles motivated us for the development of a nanowire-based quantum well infrared photodetector (NW-QWIP). The first demonstration of such a device, incorporating a GaN/AlN nanowire heterostructure that absorbs at 1.55 µm, is presented in this manuscript
Wornyo, Eric. "Nitrogen-Doped Carbon Fiber Ultramicroelectrodes as Electrochemical Sensors for Detection of Hydrogen Peroxide." Digital Commons @ East Tennessee State University, 2021. https://dc.etsu.edu/etd/3960.
Повний текст джерелаHoy, Daniel R. "Gallium Nitride and Aluminum Gallium Nitride Heterojunctions for Electronic Spin Injection and Magnetic Gadolinium Doping." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1331855661.
Повний текст джерелаKanakaraj, Sathya Narayan. "Processing Carbon Nanotube Fibers for Wearable Electrochemical Devices." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1573224577754985.
Повний текст джерелаMacpherson, Ross Fraser. "Monte Carlo modelling of Gunn devices incorporating thermal heating effects : investigations of broad frequency devices, heating effects in GaN devices and doping nucleation." Thesis, University of Aberdeen, 2009. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=203872.
Повний текст джерелаSun, Yue-Jun. "Growth and characterization of M-plane GaN and (In, Ga)N/GaN multiple quantum wells." Doctoral thesis, [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=97256375X.
Повний текст джерелаMishra, Siddharth. "Plasma Enhanced Synthesis of Novel N Doped Vertically Aligned Carbon Nanofibers-3D Graphene hybrid structure." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1552380299631335.
Повний текст джерелаXhyliu, Fjorela. "Surface Functionalization and Optical Spectroscopy of Single-wall Carbon Nanotubes." Cleveland State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=csu1599143727075125.
Повний текст джерелаDavies, Sean. "In-situ optical monitoring of growth processes during the carbon doping and nitridation of GaAs in CBE." Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.399266.
Повний текст джерелаHINOJOSA, PAOLA ALEXANDRA AYALA. "IMPLICATIONS OF THE C/N FEEDSTOCK ON CONTROLLING THE NITROGEN DOPING AND BONDING ENVIRONMENT IN CARBON NANOTUBES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=10399@1.
Повний текст джерелаOs tópicos mais importantes a ser tratados nesta tese de doutorado são os vários problemas envolvidos na síntese de nanotubos contendo nitrogênio. Isto é principalmente motivado pelas possíveis aplicações que podem ser dadas a este tipo de estruturas. A motivação central está relacionada ao fato da possibilidade de fazer dopagens tipo -p e -n em nanotubos de carbono, incorporando átomos como boro ou nitrogênio. Isto está muito longe de ser uma trivialidade devido a que devemos levar em conta que se os nanotubos de carbono forem pensados como bases estruturais para nanocompósitos e dispositivos nanoeletronicos, é necessário controlar cuidadosamente a reatividade das paredes, sua dureza mecânica e o gap eletrônico por meio de um controle da quantidade de átomos inseridos nas paredes ou entre elas. Portanto, do ponto de vista de diferentes aplicações, é importante ter a possibilidade de dopar controladamente os nanotubos. Neste trabalho apresentam-se o quadro descritivo da dependência dos parâmetros de síntese, assim como uma investigação detalhada da formação de outras estruturas co-produto do processo de formação de nanotubos. Como uma idéia pioneira proposta neste trabalho, é enfatizado o uso de fontes puras de C/N em processos de síntese baseados em deposição química na fase de vapor. Desta maneira foi possivel determinar os efeitos da atmosfera de reação e o pretratamento do catalizador como agentes favoráveis ou desfavoráveis para a síntese efetiva de nanotubos de carbono.
The main topic of this thesis is the study of various issues related to the synthesis of nitrogen containing nanotubes. This is mainly inspired in the possible applications such structures can have. The practical background lies in the fact that defined n- and p-doping of carbon nanotubes can be achieved by substituting carbon atoms from the tube walls by heteroatoms such as boron or nitrogen (N). This is far from been a triviality because we must keep in mind that if carbon nanotubes are to be used as future building blocks in nanocomposites and nanoelectronic devices, it is imperative to fine tune their wall reactivity, mechanical strength and electronic band gap by controlling the amount of foreign atoms inserted into the tube lattices. Therefore, from an applications standpoint, it is important to be able to carefully control the insertion of different dopants into nanotubes. In this work, a complete picture of the dependence on the combined synthesis parameters is established and a fundamental insight into the formation of N doped nanotubes and other structures (co- products) is provided. As a pioneering idea of this whole work, the use of pure C/N feedstocks in chemical vapor deposition methods is emphasized. With this, it was possible to determine the effects of the reaction atmosphere and the catalyst pretreatment as either favoring or disfavoring agents towards the synthesis of N-doped nanotubes.
Haugen, Neale O. "Spectroscopic Studies of Doping and Charge Transfer in Single Walled Carbon Nanotubes and Lead Sulfide Quantum Dots." University of Toledo / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1438768843.
Повний текст джерелаOgbu, Chidiebere. "Peroxide Sensing Using Nitrogen-Doped and Platinum Nanoparticle-modified Screen-Printed Carbon Electrodes." Digital Commons @ East Tennessee State University, 2019. https://dc.etsu.edu/etd/3622.
Повний текст джерелаVorobiov, Mykhailo. "PHOTOLUMINESCENCE FROM GAN CO-DOPED WITH C AND SI." VCU Scholars Compass, 2018. https://scholarscompass.vcu.edu/etd/5496.
Повний текст джерелаMokhtari, Hossein. "Transmission electron microscopy of defects and internal fields in GaN structures." Thesis, University of Bristol, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368206.
Повний текст джерелаRemesh, Nayana. "Investigation of Buffer Design and Carbon doping in AlGaN/GaN HEMTs for High Breakdown Voltages." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5463.
Повний текст джерелаChou, Chia Yi, and 周佳逸. "Influence of Buffer Carbon Doping and Buffer Thickness on Low Frequency Noise Behavior of AlGaN/GaN HEMTs." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/96035991629482509484.
Повний текст джерелаHsu, Miao-Chih, and 徐妙枝. "Isoelectronic Indium Doping Effects On P-type GaN Films." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/22909728328174972455.
Повний текст джерела國立交通大學
電子物理系
90
We have investigated the isoelecetronic indium doping effects of Indium on p-type GaN films. Two sets of samples were prepared:one is pure Mg-doped GaN film, the other is Mg-In codoped GaN film. Whether Indium is doped or not, the photoluminescence spectra of as-grown p-type GaN films all show one broad emission peak around 2.78eV, which indicating Mg-rich in all of our p-type GaN samples. Besides, it is interesting to note that the hole concentration of Mg-In codoped GaN is higher than that of Mg-doped one based on room-temperature Hall measurement data. The optimum hole concentration is 7.32´1017cm-3. We believe the increase of the hole concentration in these indium doped p-GaN films can be attributed primarily to the reduction of the acceptor activation energy, the decrease of compensation effects as well as effective incorporation of Mg atom as shallow acceptor, rather than deep impurity, not directly related to the Mg solid concentration in the film.
Fu-Min, Wang, and 王富民. "Investigation of AlGaN/GaN Doping-Channel High Electron Mobility Transistors." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/75941597127919252758.
Повний текст джерела國立高雄師範大學
電子工程學系
103
Investigation of AlGaN/GaN Doping-Channel High Electron Mobility Transistors Fu-Min Wang* Jung-Hui Tsai** Department of Electronics, National Kaohsiung Normal University, Kaohsiung, Taiwan, R.O.C Abstract In this dissertation, we will fabricate and investigate the impact of doping channel on the AlGaN/GaN doping-channel high electron mobility transistors, and the influence of doped thickness on AlGaN/GaN doping-channel high electron mobility transistors will be included. The structures were designed as follows: (1) AlGaN/GaN doping-channel high electron mobility transistor with channel doping region thickness of 20 nm (called Device A). (2) AlGaN/GaN high electron mobility transistor without GaN doping-channel layer (called Device B). (3) AlGaN/GaN doping-channel high electron mobility transistor with a channel doping region thickness of 19.5, 19, 17.5, 15, 10, and 5 nm, respectively, and with a spacer close to the AlGaN/GaN heterojunction of 0.5, 1, 2.5, 5, 10, and 15 nm, respectively (called Devices C, D, E, F, G, and H). The device (Device A) was fabricated by metal-organic chemical vapor deposition system on a sapphire substrate. The experimental results exhibit a maximum drain saturation current of 506.9 mA/mm and a maximum transconductance of 52.475 mS/mm. Also, we will simulate the DC performance of device A with doping channel according to the experimental data. The simulated characteristics are close to the experimental results by choosing the proper parameters. Simulation results show that the 2DEG concentration of the device A is higher than the device B without the doping-channel layer. The doping channel will enable the 2DEG concentration to increase. However, the impurity scattering of carriers in the doping channel will lead to the electron mobility to decrease. The results show that the device A with a doping channel has poor output saturation current, transconductance, gate leakage current, breakdown voltage, and high-frequency characteristics. In addition, the doping layer of devices C, D, E, F, G, and H are away from the 2DEG. It can decrease the effect of impurity scattering. The result exhibits that the DC and high-frequency characteristics of the devices F, G, and H are better than the device B. In the devices F, G, and H, the 2DEG carrier concentrations are 1.158 × 1020, 1.155 × 1020, and 1.154 × 1020 cm-3, the maximum output currents are of 672, 682, and 689.7 mA/mm, and transconductance are 84.4, 87, and 89.4 mS/mm, respectively. Furthermore, the unity gain cut-off frequencies are 17.8, 18.1, and 18.3 GHz, and maximum oscillation frequencies are 28.3, 29.1, and 29.2 GHz respectively. * Author ** Advisor KEYWORDS : AlGaN/GaN, high electron mobility transistor, doping channel, impurity scattering
Maubane, Manoko Stephina. "Synthesis, doping and functionalization of carbon nanotubes." Thesis, 2011. http://hdl.handle.net/10539/9148.
Повний текст джерелаKuo, Hsin-Fu, and 郭信甫. "Functionalized Carbon Nanotubes:Surface Decoration and Doping Effect." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/63859799801652308387.
Повний текст джерела國立清華大學
材料科學工程學系
95
Abstract The works presented in this thesis discuss the effects of non-covalent interaction with carbon nanotubes and molecules as well as Boron-dopants modify electronic structure of carbon nanotubes. Surface decoration has been proved to be important in changing the physico-chemical properties of nanotubes. For example, surface tension, gas sensing and purification via surface reaction are discussed in this study. Doping is well known effective in changing electrical properties of Si-based devices, and it also works in carbon nanotubes. In this study, we demonstrate how bending effect electrical properties in Boron-doped carbon nanotubes (BCNTs) and single-walled carbon nanotubes (SWCNTs). Chapter 1 introduces the basic concept of nanotubes surface decoration by different molecules, e.g. polymers, surfactants, and others chemical species. Two attachments will be discussed, inside and outside the tube, along with the influence of infrared spectroscope analyses. Chapter 2 will discuss the experimental methods, and characterization techniques employed in this study. Chapter 3 shows the ammonia blast on nanotube surface. This work demonstrates the removal of carbonaceous impurities and catalytic particles from carbon nanotube surfaces by ammonia explosion and data reveals that gas sensitivity of purified nanotubes becomes faster by a factor of 3.8 compared with pristine materials. Chapter 4 discusses the observations of surface tension change upon NH3 attachment and droplet (deionized water) migration on nanotube surface. Droplet moving rate, surface tensions of pristine and decorated nanotube films are calculated from experiment information. Feasible mechanism is proposed and influence of droplet migration by external magnetic field is also predicted. Chapter 5 mainly focuses on electron tunneling through boron doped carbon nanotubes. We also show the difference electronic behavior between undoped and B-doped nanotubes. In this chapter, we describe the phenomenon of nanotube deflection driven electron transmission. Chapter 6 concludes results of our experiments.
Yang, Yi Chang, and 楊益菖. "Effect on Photoelectric Characteristics of Blue Light-Emitting Diodes by Doping in InGaN of GaN/InGaN/GaN." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/68017258889013245799.
Повний текст джерелаShu, Chen-Ke, and 徐宸科. "The Characterizations and Studies of Doping and Ion-Implantation Effects in GaN Films." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/21905049296363340543.
Повний текст джерела國立交通大學
電子物理系
89
The structural and optical properties of impurity doped and P-implanted GaN films were studied by using Raman scattering, photoluminescence, photoluminescence excitation, time-resolved photoluminescence, scanning electronic microscopy, atomic force microscopy, X-ray diffraction, and Hall measurements. The electron concentration reached as high as 1.3x10^19 cm^-3 without cracks or nanopits by using the Si dopant. The solid-vapor ratio was also high about 0.055. The band gap shrinkage of GaN:Si was observed that is proportional to n^{1/3}. In GaN:Mg, we observed the blue-shifts in both X-ray and Raman peaks indicating that Mg dopants possibly replace Ga atoms. The excitation power dependence of photoluminescence were examined. The blue-violet band intensity slowly decreases under continuous wave pumping reflecting the metastable behavior, that may account for the mechanism of the 430 nm peak, and an optical potential barrier of 69 meV was obtained. The isoelectronic In-doping with an adequate TMIn flow rate was found to improve the electrical, crystalline and optical qualities of GaN films. They also show improved surface smoothness with greatly reduced nanopits. More importantly, isoelectronic doping has caused the PL linewidth of the donor-bound exciton emission of GaN to decrease sharply to 10 meV or less at 15 K. The recombination dynamics of GaN:In were also studied by time-resolved photoluminescence. The recombination lifetime decreases sharply to 30 ps, regardless of the measured temperature and the TMIn flow rate that could be related to the intrinsic relaxation channel of the isoelectronic In doping. The P-implantation effects on GaN and the mechanism of yellow luminescence were studied. We also examined the rapid thermal annealing (RTA) effects. The localized states in GaN:P were observed that are different from the step absorption in as-grown GaN. After the RTA processes, the Hall concentration and mobility recovered to the initial values of the as-grown GaN and even slightly better than that. From the Arrhenius plot, the binding energy of the P-iso trap and ionization energy were obatined. For As-doping, we observed that the growth temperature window can be extended to about 900 ℃. The Hall concentration decreased from 3x10^18 to 5x10^17 cm^-3 and the mobility is about 150 cm/V.s. We believed that the proper As-doping indeed helps the electrical properties and crystalline structures. The exciton recombination dynamics were also studied and compared to that of In-doped GaN. The decay time was measured to be temperature dependent and interpreted by the competition between the intrinsic impurity levels and As-induced shallow-acceptor-like levels.