Rozprawy doktorskie: „Semiconductor metal interface”

1

Denk, Matthias. "Structural investigation of solid liquid interfaces metal semiconductor interface /". [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-29148.

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2

Maani, Colette. "A study of some metal-semiconductor interfaces". Thesis, University of Ulster, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329499.

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3

Palmgren, Pål. "Initial stages of metal- and organic-semiconductor interface formation". Licentiate thesis, KTH, KTH, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3911.

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This licentiate thesis deals with the electronic and geometrical properties of metal-semiconductor and organic-semiconductor interfaces investigated by photoelectron spectroscopy and scanning tunneling microscopy.

First in line is the Co-InAs interface (metal-semiconductor) where it is found that Co is reactive and upon adsorption and thermal treatment it alloys with the indium of the substrate to form metallic islands, about 20 nm in diameter. The resulting broken bonds causes As entities to form which are loosely bond to the surface and evaporate upon thermal treatment. Thus, the adsorption of Co results in a rough interface.

Secondly the metal-free phthalocyanine (H₂PC) - titanium dioxide interface (organic-semiconductor) is investigated. Here it is found that the organic molecules arrange themselves along the substrate rows upon thermal treatment. The interaction with the TiO₂ is mainly with the valence Π-electrons in the molecule causing a relatively strong bond, but this interaction is short range as the second layer of molecules retains their molecular character. This results in an ordered adsorption but limited mobility of the molecules on the surface prohibiting well ordered close packed layers. Furthermore, the hydrogen atoms inside the cyclic molecule leave the central void upon thermal treatment.

The third case is the H₂PC-InAs/InSb interface (organic-semiconductor). Here ordered overlayer growth is found on both substrates where the molecules are preferentially adsorbed on the In rows in the [110] direction forming one-dimensional chains. The InSb-H₂PC interface is found to be weakly interacting and the bulk-like molecular character is retained upon both adsorption and thermal treatment. On the InAs-H₂PC interface, however, the interaction is stronger. The molecules are more affected by the surface bond and this effect stretches up a few monolayers in the film after annealing.

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4

Yan, Yu. "Interface magnetic properties in ferromagnetic metal/semiconductor and related heterostructures". Thesis, University of York, 2018. http://etheses.whiterose.ac.uk/20412/.

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This dissertation investigates the growth and magnetic properties of magnetic thin films deposited on semiconductor GaAs and the insulator MgO, which could be useful for devices such as Spin-FET and MRAM. CoFeB amorphous films were grown on both GaAs and MgO. We have studied the origin of the uniaxial magnetic anisotropy (UMA) and perpendicular magnetic anisotropy (PMA) with TEM, VSM and XMCD. Our results demonstrated that the orbital moment of Co atoms play an important role to both UMA and PMA. The origin of UMA in Fe/GaAs (100) system with Cr interlayers is explored. The values of UMA in the Fe/GaAs systems were found to be dependent on the thickness of Cr interlayer by the SQUID-VSM measurements. RHEED patterns and TEM images offered the morphology and crystalline structure information of different layers in the samples. Our results show that the UMA disappears when the interlayer Cr forms continuous film of around 5 ML. This offers direct evidence for the first time that the origin of UMA is from the interface bonding rather than the lattice mismatch related film stress. Finally, Fe films were deposited onto GaAs (100) substrate with a heavy metal element Au interface layer. The enhancement of UMA was found in the Fe/Au/GaAs system by the VSM measurements. The XMCD results show that the orbital moment of Fe is enhanced when the Au interlayer is under 0.5 ML, which leads to the enhancement of the UMA in the Fe/Au/GaAs system. Results from the three different systems provide an important understanding of the research into the interface magnetic properties of ferromagnetic metal/semiconductors. These interesting discoveries are very useful for the development of next generation electronic devices like MRAM and SpinFET.

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5

Evans, D. A. "The metal-indium phosphide (110) interface : Interactions and Schottky barrier formation". Thesis, Bucks New University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234721.

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6

Moran, John Thomas. "The electronic structure of gold-induced reconstructions on vicinal silicon(111)". Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.283057.

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7

Huang, Chender 1960. "Characterization of interface trap density in power MOSFETs using noise measurements". Thesis, The University of Arizona, 1988. http://hdl.handle.net/10150/276872.

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Low-frequency noise has been measured on commercial power MOSFETs. These devices, fabricated with the VDMOS structure, exhibit a 1/f type noise spectrum. The interface state density obtained from noise measurements was compared with that obtained from the subthreshold-slope method. Reasonable agreement was found between the two measurements. The radiation effects on the noise power spectral density were also investigated. The results indicated that the noise can be attributed to the generation of interface traps near the Si-SiO₂ interface. The level of interface traps generated by radiation was bias dependent. The positive gate bias gave rise to the largest interface-trap density.

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8

Zavaliche, Florin. "The metal-semiconductor interface Fe-Si(001) and Fe-InP(001) /". [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=965216217.

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9

Walters, Stephanie A. "The metal - n-type gallium antimonide (110) interface : interfacial reactions and Schottky barrier formation". Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238197.

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10

Metcalf, Frances L. "The noble metal/elemental semiconductor interface (a study of Ag on Ge(111))". Thesis, University of Sussex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.306595.

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11

Yano, Hiroshi. "Control of Electronic Characteristics at SiO_2/SiC Interface for SiC Power Metal-Oxide-Semiconductor Devices". 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150681.

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12

Racke, David. "Measuring and Controlling Energy Level Alignment at Hybrid Organic/Inorganic Semiconductor Interfaces". Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/556212.

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In this dissertation, I present the results of my research regarding hybrid semiconductor interfaces between organic and inorganic semiconductors. Using photoemission spectroscopy, I elucidate the important role of defect-induced electronic states within the inorganic semiconductor phase. These states significantly affect both the energy level alignment and the charge carrier dynamics at the hybrid interface. I demonstrate that the behavior of these hybrid semiconductor interfaces is complex and not well characterized by current models for organic semiconductor interfaces. Specifically, I show that hybrid interfaces host unique electronic phenomena that depend sensitively on the surface structure of the inorganic semiconductor. I also demonstrate new applications of photoemission spectroscopies that enable the direct analysis of important properties of inorganic semiconductors, including charge carrier behavior near hybrid interfaces and the electronic character of defect-induced energy levels. The research presented here focuses on two different n-type inorganic semiconductors, tin disulfide (SnS₂) and zinc oxide (ZnO). SnS₂ is a layered transition metal dichalcogenide that presents an atomically flat and inert surface, ideal for sensitively probing electronic interactions at the hybrid interface. To probe the electronic structure of the SnS₂ surface, I used a variety of organic molecules, including copper phthalocyanine, vanadyl naphthalocyanine, chloro-boron subphthalocyanine, and C₆₀. ZnO has a complex surface structure that can be modified by simple experimental procedures; it was therefore used as a tunable semiconductor substrate where the effects of altered electronic structure can be observed. By carefully studying the origin of hybrid interfacial interactions, these research projects provide a first step in explicitly elucidating the fundamental mechanisms that determine the electronic properties of hybrid interfaces.

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13

Fonseca, James Ernest. "Accurate treatment of interface roughness in nanoscale double-gate metal oxide semiconductor field effect transistors using non-equilibrium Green's functions". Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1176318345.

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14

Hossain, Md Tashfin Zayed. "Electrical characteristics of gallium nitride and silicon based metal-oxide-semiconductor (MOS) capacitors". Diss., Kansas State University, 2013. http://hdl.handle.net/2097/16942.

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Doctor of Philosophy
Department of Chemical Engineering
James H. Edgar
The integration of high-κ dielectrics with silicon and III-V semiconductors is important due to the need for high speed and high power electronic devices. The purpose of this research was to find the best conditions for fabricating high-κ dielectrics (oxides) on GaN or Si. In particular high-κ oxides can sustain the high breakdown electric field of GaN and utilize the excellent properties of GaN. This research developed an understanding of how process conditions impact the properties of high-κ dielectric on Si and GaN. Thermal and plasma-assisted atomic layer deposition (ALD) was employed to deposit TiO₂ on Si and Al₂O₃ on polar (c-plane) GaN at optimized temperatures of 200°C and 280°C respectively. The semiconductor surface treatment before ALD and the deposition temperature have a strong impact on the dielectric’s electrical properties, surface morphology, stoichiometry, and impurity concentration. Of several etches considered, cleaning the GaN with a piranha etch produced Al₂O₃/GaN MOS capacitors with the best electrical characteristics. The benefits of growing a native oxide of GaN by dry thermal oxidation before depositing the high-κ dielectric was also investigated; oxidizing at 850°C for 30 minutes resulted in the best dielectric-semiconductor interface quality. Interest in nonpolar (m-plane) GaN (due to its lack of strong polarization field) motivated an investigation into the temperature behavior of Al₂O₃/m-plane GaN MOS capacitors. Nonpolar GaN MOS capacitors exhibited a stable flatband voltage across the measured temperature range and demonstrated temperature-stable operation.

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15

Nakazawa, Satoshi. "Interface Charge Engineering in AlGaN/GaN Heterostructures for GaN Power Devices". Kyoto University, 2019. http://hdl.handle.net/2433/244553.

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16

Streb, Fabian. "Novel materials for heat dissipation in semiconductor technologies". Eigenverlag, 2018. https://monarch.qucosa.de/id/qucosa%3A23536.

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Thermal management is a major bottleneck for the next-but-one generation of semiconductor devices, especially the performance of SiC and GaN devices is limited by heat dissipation. This thesis evaluates four new packaging concepts with regards to thermal management: Diamond based substrates, phase change materials, Cu-Graphene composite films and anisotropic heat dissipation. Anisotropic heat dissipation is shown to be the most auspicious concept. A metal-matrix composite baseplate for a high performance power module using annealed pyrolytic graphite is created and evaluated. The baseplate shows a locally increased heat dissipation compared to a plain metal baseplate by 30 %. Furthermore, the thermal contact between device (baseplate) and cooler is of high importance. A study of different characterization methods for thermal interface materials is performed and a new method for the quantification of the thermal contact conductance is presented. The study shows that a combination of several methods is necessary so that the complete picture of heat dissipation performance of thermal interface materials becomes apparent. The new developed method allows to select the perfect thermal grease for a given combination of device and cooler.
Wärmemanagement ist eine große Herausforderung sowohl für aktuelle als auch für zukünftige Halbleiterprodukte. Speziell die nächste Produktgeneration mit SiC oder GaN Chips benötigen neue Entwärmungskonzepte, um ihr volles Potential bezüglich höherer Stromstärken zu entfalten. In dieser Arbeit wurden vier neuartige Konzepte erforscht: Diamant basierte Substrate, Phasen-Wechsel-Materialien, Cu-Graphene Kompositschichten und anisotrope Entwärmung. Es zeigte sich, dass anisotrope Entwärmung das vielversprechendste Konzept ist. Als Demonstrator wurde eine Bodenplatte mit thermisch pyrolytischen Graphiteinleger für ein Leistungsmodul gefertigt. Sie zeigt eine lokale Erhöhung der Entwärmung von 30 %. Weiter ist der thermische Kontakt zwischen Bauteil und Kühler sehr wichtig. Verschiedene Charakterisierungsmethoden für thermische Schnittstellen-Materialien wurden verglichen. Dieser Vergleich zeigt, dass eine Kombination verschiedener Methoden notwendig ist, um ein vollständiges Bild über die Leistungsfähigkeit solcher Materialien zu gewinnen. Eine neue Messmethode wurde entwickelt, um die thermische Kontakt-Leitfähigkeit zu messen. Diese neue Methode ermöglicht es, die beste Wärmeleitpaste für eine vorgegebene Kombination aus Produkt und Kühleroberfläche zu identifizieren.

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17

Djeghloul, Fatima Zohra. "Study of organic semiconductor / ferromagnet interfaces by spin-polarized electron scattering and photoemission". Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01062352.

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I studied organic semiconductor/ferromagnet interfaces by characterizing them by spin-polarized electron scattering and photoemission spectroscopy experiments. In the first part, a completely unexpected behaviour of the spin-dependent electron reflection properties of these interfaces is observed. In fact, sub-monolayer coverage of the organic molecules makes the electron reflection amplitude independent of the spin, i.e. both the reflectivity and the reflection phase become independent of the spin orientation of the incident electrons. Although I am not able at the moment to identify the cause of this phenomenon, I show that it is a very general phenomenon which is independent of the energy of the primary electrons, the choice of the ferromagnetic substrate, the choice of the organic molecule, and of the orientation of the initial spin polarization. It is not due to a change of the surface magnetization, a depolarization of the primary electrons, or a direct interaction of the molecules with the ferromagnetic substrate. Moreover, theory does not predict so far the experimental results and further research is required to unveil the physics behind these observations. In the second part of my thesis, spin-resolved photoemission experiments have been performed at the synchrotron SOLEIL. The main result is the observation of a highly spin-polarized molecule-induced electronic state close to the Fermi level. Measurements as a function of the organic layer thickness allow us to determine the interfacial character of this electronic state. Finally, these results are compared with theoretical calculations performed at the institute.

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18

Cai, Wei. "Ballistic Electron Emission Microscopy and Internal Photoemission Study on Metal Bi-layer/Oxide/Si, High-k Oxide/Si, and “End-on” Metal Contacts to Vertical Si Nanowires". The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269521615.

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19

Kobayashi, Takuma. "Study on Defects in SiC MOS Structures and Mobility-Limiting Factors of MOSFETs". Kyoto University, 2018. http://hdl.handle.net/2433/232043.

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20

Fichou, Denis. "L'interface oxyde de zinc/électrolyte : étude des processus primaires". Paris 6, 1986. http://www.theses.fr/1986PA066259.

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21

Charlesworth, Jason. "Electronic structure of metal-semiconductor interfaces". Thesis, University of Cambridge, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239738.

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22

Badoz, Pierre-Antoine. "Propriétés de transport électronique dans les hétérostructures métal/semiconducteur". Grenoble 1, 1988. http://www.theses.fr/1988GRE10024.

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Le travail porte principalement sur l'etude des proprietes de transport electronique dans les films metalliques ultraminces de cosi::(2) (10 a 20 angstroems) epitaxies sur du silicium. Les principaux points abordes concernent: le transport perpendiculaire, le transport parallele aux interfaces, les proprietes electroniques des siliciures

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23

Tallarida, Massimo. "Electronic properties of semiconductor surfaces and metal, semiconductor interfaces". [S.l.] : [s.n.], 2005. http://www.diss.fu-berlin.de/2005/196/index.html.

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24

Curson, Neil Jonathan. "Growth and structure at metal-semiconductor interfaces". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388320.

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25

Rouvière, Jean-Luc. "Structure atomique des joints de grains de flexion d'axe <001> dans le silicium et le germanium". Grenoble 1, 1989. http://www.theses.fr/1989GRE10010.

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Etude de cinq joints de grains de flexion d'axe 001, de grande coincidence (sigma=5, 65, 13, 25 et 41) par microscopie electronique haute resolution et relaxation numerique. Presentation d'une analyse en termes d'unites structurales-dislocation

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26

Makineni, Anil Kumar. "Construction and realisation of measurement system in a radiation field of 10 standard suns". Thesis, Mittuniversitetet, Institutionen för informationsteknologi och medier, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:miun:diva-17209.

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A measurement system is to be presented, which is used to obtain the I-V characteristics of a solar cell and to track its temperature during irra-diation before mounting it into a complete array/module. This project presents both the design and implementation of an Electronic load for testing the solar cell under field conditions of 10000 W/m^2, which is able to provide current versus voltage and power versus voltage charac-teristics of a solar cell using a software based model developed in Lab-VIEW. An efficient water cooling method which includes a heat pipe array system is also suggested. This thesis presents the maximum power tracking of a solar cell and the corresponding voltage and current values. In addition, the design of the clamp system provides an easy means of replacing the solar cell during testing.Keywords: Solar cell, Metal Oxide Semiconductor Field Effect Transistor (MOSFET), I-V characteristics, cooling system, solar cell clamp system, LabVIEW, Graphical User Interface (GUI).

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27

Gregory, David. "Charge transfer studies of alkali-metal/semiconductor interfaces". Thesis, University of Liverpool, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240051.

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28

Unsworth, Paul. "Spectroscopic studies of metal alloys and semiconductor interfaces". Thesis, University of Liverpool, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343647.

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29

Wang, Zhiqiang. "Studies of the liquid metal and semiconductor interfaces /". The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487676261010274.

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30

Schuerlein, Thomas John. "Chemisorption in organic semiconductor systems: Investigation of organic semiconductor-organic semiconductor and organic semiconductor-metal interfaces". Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187068.

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The production of ordered thin films of organic monolayers is of general interest to the surface science community and of specific interest to our laboratory where the understanding of small molecule adsorption has been a long term goal. The production of ordered thin films may simplify the study of the interactions of adsorbate molecules on organic films. The production of ordered layers of aromatic hydrocarbons and dye molecules were performed under a variety of deposition conditions in an ultrahigh vacuum (UHV) environment. These films were studied with several UHV analytical techniques including low energy electron diffraction, photoelectron spectroscopies, thermal program desorption mass spectrometry and visible spectroscopy. The study of several aromatic hydrocarbons revealed that these molecules possess significant mobility on the Cu(100) surface, while adsorbing with their molecular plane parallel to the copper surface. A majority of phthalocyanine (Pc) molecules studied were observed to adsorb in a single packing structure at similar substrate temperatures for divalent metal centers and a slightly higher temperature for trivalent metal centers. Chloroaluminum phthalocyanine was determined to pack in a unique structure at 150°C and adopt the previously observed phthalocyanine structure at 175°C. It was determined that the perylene derivatives 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) and N, N-dimethyl-3,4,9,10-perylene-bis(carboxylimide) (DMPI) dissociatively interact with a Cu(100) surface while forming an epitaxial overlayer. These two structurally similar molecules were determined to possess different growth modes at the initial stages of growth, which was attributed to their different bulk packing structures. The electronic properties of a Pc-PTCDA heterostructure were investigated via ultraviolet photoelectron spectroscopy. The investigation correctly anticipated the diode behavior of this isotype heterostructure. This study also proved the validity of the electron affinity rule, developed for inorganic structures, for organic systems.

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31

Sun, Zhuting. "Electron Transport in High Aspect Ratio Semiconductor Nanowires and Metal-Semiconductor Interfaces". University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479821421998919.

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32

Todescato, Francesco. "Functional dielectric/semiconductor and metal/semiconductor interfaces in organic field-effect transistors". Doctoral thesis, Università degli studi di Padova, 2007. http://hdl.handle.net/11577/3425125.

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The work presented in this thesis focuses on the investigation of two interfaces which play a crucial role in the physics of organic electronic devices: the dielectric/organic semiconductor and the organic semiconductor/metal ones. Regarding the dielectric/OS interface, we have deeply investigated the relationship between the SiO2 cleaning protocol or treatment and the electrical response of OFETs based on two PPV semiconducting polymers (MEH-PPV and OC1C10-PPV) and on a quarterthiopene derivative small molecule (DHCO-4T). Regarding the OS/metal interface, we investigated the electrical performances of PPV and DHCO-4T based OFETs with different metal contacts.

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Müller, Kathrin. "Organic semiconductor interfaces with insulators and metals". Göttingen Cuvillier, 2009. http://d-nb.info/997890533/04.

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34

凌志聰 i Chi-chung Francis Ling. "Positron beam studies of the metal-GaAs (110) interface". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B31211689.

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Ling, Chi-chung Francis. "Positron beam studies of the metal-GaAs (110) interface /". [Hong Kong : University of Hong Kong], 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13781443.

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Wang, Chenggong. "Interface Studies of Organic/Transition Metal Oxide with Organic Semiconductors and the Interfaces in the Perovskite Solar Cell". Thesis, University of Rochester, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3723336.

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In recent decades, research and development of organic based semiconductor devices have attracted intensive interests. One of the most essential elements is to understand the electronic structures at various interfaces involved in these devices since the interface properties control many of the critical electronic processes. It is thus necessary to study the electronic properties of the organic semiconductors with surface analytical tools to improve the understanding of the fundamental mechanisms involved in the interface formation. This thesis covers the experimental investigations on some of the most interesting topics raised in the recent development of organic electronic devices. The thesis intends to reveal the physical processes at the interface and their contribution to the device performance with photoemission and inverse photoemission investigations on the evolution of the occupied and unoccupied electronic structures. I will report a substantial difference in the electron affinity of CuPc on two substrates as the orientations of CuPc are different. I will also illustrate that the CuPc has standing up configuration on one monolayer of C60 on SiO2 while lying down on one monolayer of C60 on HOPG. Meanwhile, the CuPc on more than one monolayers of C60 on different substrates show that the substrate orientation effect vanished. Then I will propose a two-stage model to describe the bulk doping effect of C60 by molybdenum oxide. I will also demonstrate that the doping effect of C60 by ultra-thin layer molybdenum oxide is weaker than that by interface doping and bulk doping. I will demonstrate that for Au on CH3NH3PbI3, hole accumulation occurs at the vicinity of the interface, facilitating hole transfer from CH3NH3PbI3 to Au. I will show a strong initial shift of core levels to lower binding energy in C60 on CH3NH3PbI3 interface, which indicates that electrons transfer from the perovskite film to C60 molecules. I will further demonstrate that the molybdenum oxide surface can be passivated by approximately two monolayers of organic thin films against exposure to air. I will discuss the mechanism that how oxygen plasma treatment effectively recover the high work function drop of molybdenum oxide by air exposure. At the end, I will show that a small energy offset at Pentacen/C60 heterojunction makes it easy to transfer electrons from Pentacene to C60 even under a small applied bias, facilitating the occurrence of charge generation. Finally, I will summarize the thesis.

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37

Kiely, C. J. "An electron microscopy study of some metal-semiconductor interfaces". Thesis, University of Bristol, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375011.

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38

Anandan, C. "Metal contacts to undoped a-Si:H: interface modification and Scottky barrier characteristics". Thesis, Cardiff University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314636.

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39

Esfandiari, Hossein. "Ion beam mixing of nickel and cobalt films on silicon". Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304593.

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40

O'Keefe, Matthew Francis. "Optimisation of contacts for indium phosphide millimetre-wave devices". Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277202.

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41

Blomfield, Christopher James. "Study of surface modifications for improved selected metal (II-VI) semiconductor based devices". Thesis, Sheffield Hallam University, 1995. http://shura.shu.ac.uk/19362/.

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Metal-semiconductor contacts are of fundamental importance to the operation of all semiconductor devices. There are many competing theories of Schottky barrier formation but as yet no quantitative predictive model exists to adequately explain metal-semiconductor interfaces. The II-VI compound semiconductors CdTe, CdS and ZnSe have recently come to the fore with the advent of high efficiency photovoltaic cells and short wavelength light emitters. Major problems still exist however in forming metal contacts to these materials with the desired properties. This work presents results which make a significant contribution to the theory of metal/II-VI interface behaviour in terms of Schottky barriers to n-type CdTe, CdS and ZnSe. Predominantly aqueous based wet chemical etchants were applied to the surfaces of CdTe, CdS and ZnSe which were subsequently characterised by X-ray photoelectron spectroscopy. The ionic nature of these II-VI compounds meant that they behaved as insoluble salts of strong bases and weak acids. Acid etchants induced a stoichiometric excess of semiconductor anion at the surface which appeared to be predominantly in the elemental or hydrogenated state. Alkaline etchants conversely induced a stoichiometric excess of semiconductor cation at the surface which appeared to be in an oxidised state. Metal contacts were vacuum-evaporated onto these etched surfaces and characterised by current-voltage and capacitance-voltage techniques. The surface preparation was found to have a clear influence upon the electrical properties of Schottky barriers formed to etched surfaces. Reducing the native surface oxide produced near ideal Schottky diodes. An extended study of Au, Ag and Sb contacts to [mathematical formula] substrates again revealed the formation of several discrete Schottky barriers largely independent of the metal used; for [mathematical formula]. Deep levels measured within this study and those reported in the literature led to the conclusion that Fermi level pinning by native defects is a dominant mechanism in Schottky barrier formation in these systems.

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李加碧 i Stella Li. "Interface state generation induced by Fowler-Nordheim tunneling in mosdevices". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221403.

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Razgoniaeva, Natalia Razgoniaeva. "Photochemical energy conversion in metal-semiconductor hybrid nanocrystals". Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1465822519.

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Wu, Zhenghui. "Impact of metal oxide/bulk-heterojunction interface on performance of organic solar cells". HKBU Institutional Repository, 2015. https://repository.hkbu.edu.hk/etd_oa/159.

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Organic photovoltaics have shown much promise as an alternative photovoltaic technology for application in low-cost, large-scale and flexible solar cells. The application of metal oxides in organic solar cells (OSCs) and the impact of the properties of metal oxide/organic hetero-interfaces on cell performance have attracted a lot of attention. The metal oxide/organic interfaces have a crucial impact on interfacial charge transfer, charge collection and the overall device performance. This thesis is aimed at clarifying the principal interfacial phenomena occurring at the metal oxide/organic hetero-interfaces as well as effective engineering of those interfacial properties in OSCs. Photo-generated electrons and holes undergo different recombination processes, e.g., bimolecular recombination and trap-assisted recombination, before being collected by the electrodes in OSCs. Light intensity-dependent current densityvoltage (JV) characteristics of OSCs were analyzed to study the effect of recombination on charge collection efficiency. Effect of metal oxide/organic hetero-interfaces on charge transfers at organic/electrode interface was analyzed using transient photocurrent (TPC) measurements. Light intensity-dependent JV characteristics and TPC characteristics were applied to explore the charge recombination dynamics in OSCs with a metal oxide interlayer. This project concentrated on an in-depth investigation of the physics and the interface phenomena such as interfacial exciton dissociation, charge recombination processes, charge collection and interface engineering for high performing OSCs. The fundamentals about light intensity-dependent J-V characteristics for OSCs were summarized. The relationship between the charge recombination dynamics and light intensity-dependent J-V characteristics in OSCs were developed. Light intensity-dependent JSC, VOC and FF in OSCs made with different bulk-heterojunction (BHJ) systems of PTB7:PC70BM, PTB7-Th:PC70BM and PNB4:PC70BM were investigated. It is found that bimolecular recombination is the most prominent factor limiting the performance of OSCs. For freshly made OSCs fabricated based on the commercial polymers, e.g. PTB7 & PTB7-Th, and the new polymer PNB4 synthesized in-house, the trap-assisted charge recombination process in the BHJ active layer plays a relatively small role. This suggests that reducing the bimolecular recombination in OSCs through selecting proper materials and device structures is crucial for enhancing the power conversion efficiency (PCE) of OCSs. In this work, device structures which enable reducing bimolecular recombination in OSCs were investigated. The effect of ZnO interlayer at the interface between BHJ and Al cathode on the performance of PTB7:PC71BM based OSCs was studied by a combination of theoretical simulation and experimental characterization techniques, e.g., using light intensity-dependent JV characteristic and TPC measurements etc. It shows that ZnO interlayer has a profound effect on the performance of the PTB7:PC70BM-based OSCs, although it does not have a significant influence on the maximum absorptance in the active layer. The origin of the improvement in the cell performance is associated with the efficient charge collection due to the favorable exciton dissociation at the electrode/active layer interface. It is shown that the presence of the ZnO interlayer allows using a thinner active layer without moderating the absorption in the optically optimized control OSCs without the ZnO interlayer. OSCs with a ~10 nm thick ZnO interlayer are found to be favorable for the efficient charge collection, and thereby improving the cell performance. The TPC measurements also reveal that the dissociation of excitons at the metal/organic interface of regular OSCs hinders the electron collection. The unfavorable interfacial exciton dissociation can be removed by interposing a ZnO interlayer at the Al/organic interface, thus bimolecular recombination at the electrode/active layer interface can be reduced for improving the charge collection efficiency. PCE of the OSCs using ZnO interlayer was 6.5%, which is about 20% higher than a control cell (5.4%), having an identical device configuration without a ZnO interlayer. Solution-processed anode interlayer, a mixture of solution-processed MoOX and PEDOT:PSS, was adopted for application in inverted PTB7:PC71BM-based OSCs. The ratio of MoOX to PEDOT:PSS in the mixed solution was optimized for achieving the best cell performance. A PCE of 7.4% was obtained for OSCs with an optimal MoOX-PEDOT:PSS based interlayer, interposed between the BHJ active layer and Ag anode, which means 10% enhancement over the PCE of control cell made with an evaporated MoOX interlayer. Light intensity-dependent JV characteristics implied that the bimolecular recombination in OSCs with a MoOX-PEDOT:PSS interlayer was reduced. TPC measurements showed that the favorable exciton dissociation occurs at the organic/MoOX interface for the inverted OSCs. The favorable interfacial exciton dissociation generates an electrical field within a very small space near the interface, contributing significant additional photocurrent when the effective bias across the active layer in the OSCs is low, and thereby assisting in an efficient charge collection at the organic/electrode interface. In addition to the improvement in the cell performance, the solution-processed MoOX-PEDOT:PSS interlayer does not require a post-annealing treatment, which is beneficial for application in solution-processed tandem and flexible OSCs.

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Li, Stella. "Interface state generation induced by Fowler-Nordheim tunneling in mos devices /". Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B20566487.

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ANTOINE, ANNE-MARIE. "Mecanismes de croissance et de constitution d'interfaces dans les couches minces de semiconducteurs amorphes hydrogenes etudies par ellipsometrie spectroscopique in situ". Paris 7, 1987. http://www.theses.fr/1987PA077179.

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Etude de la croissance de couches minces de silicium, germanium et d'alliages silicium-germanium amorphes hydrogenes deposees par decomposition radiofrequence de silane, germane et d'hydrogene. Etude des mecanismes d'initiation de la couche en fonction des conditions de preparation. Analyse de l'influence de la nature du support sur le depot des premieres couches monomoleculaires

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胡一帆 i Yi-fan Hu. "Positron beam studies on the electric field at metal-semiinsulating GaAs interfaces". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1997. http://hub.hku.hk/bib/B31215312.

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Hu, Yi-fan. "Positron beam studies on the electric field at metal-semiinsulating GaAs interfaces /". Hong Kong : University of Hong Kong, 1997. http://sunzi.lib.hku.hk/hkuto/record.jsp?B19036620.

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Zhu, Xingguang Williams John R. "Alternative growth and interface passivation techniques for SiO2 on 4H-SiC". Auburn, Ala, 2008. http://hdl.handle.net/10415/1494.

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Maxisch, Thomas. "Ab initio study of interface states at metal contacts to III-IV semiconductors /". Lausanne, 2003. http://library.epfl.ch/theses/?display=detail&nr=2890.

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Thèse sciences, EPF Lausanne, no 2890 (2003), Faculté Sciences de base SB, Section de physique (Institut de théorie des phénomènes physiques). Directeur: A. Baldereschi ; rapporteurs: H. Beck ... et al.

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