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Author: Leyla Colakerol Publisher: ISBN: Category : Languages : en Pages : 308
Book Description
Abstract: Narrow band gap semiconductors play a crucial role in thin film photovoltaic cells and optoelectronics devices operating in the infrared region of visible spectrum. The interactions between the valence and conduction bands due to the narrow band gap have a big influence on the electronic structure and the device performance of these materials. The surface and bulk electronic properties of narrow band gap semiconductors were investigated using angle resolved photoelectron spectroscopy (ARPES), x-ray absorption spectroscopy and x-ray emission spectroscopy. Comparisons were made between the experimental results and density functional theory band structure calculations. Intrinsic electron accumulation near the surface of clean InN was directly observed by ARPES. The accumulation layer is discussed in terms of the bulk Fermi level (E F) lying below the pinned surface E F, with a confining potential formed normal to surface due to the downward band bending facilitated by donor type surface states or nitrogen vacancies. Various spectroscopic techniques were used to measure this band bending. The energy of the Fermi level and the size of the Fermi surface for these quantum well states could be controlled by varying the method of surface preparation and by the adsorption of potassium on the surface. Intermixing between the heavy and light hole valence bands in the intrinsic quantum well potential associated with the surface electron accumulation layer results in an inverted band structure, with the valence band maximum lying away from the Brillouin zone center. Similarly, the electronic band structure of CdO was investigated and quantized electron subbands were observed above the valence band maximum. The origin of the accumulation layer is discussed in terms of the bulk band structure of CdO calculated using quasi particle corrected density functional theory. High electron density at the surface of these materials provides new opportunities for potential device structures such as sensors, high frequency transmitters and field effect transistors. Therefore the study of their near surface electron accumulation and electronic structure is of importance in understanding the properties of these materials and discovering new application areas.
Author: Leyla Colakerol Publisher: ISBN: Category : Languages : en Pages : 308
Book Description
Abstract: Narrow band gap semiconductors play a crucial role in thin film photovoltaic cells and optoelectronics devices operating in the infrared region of visible spectrum. The interactions between the valence and conduction bands due to the narrow band gap have a big influence on the electronic structure and the device performance of these materials. The surface and bulk electronic properties of narrow band gap semiconductors were investigated using angle resolved photoelectron spectroscopy (ARPES), x-ray absorption spectroscopy and x-ray emission spectroscopy. Comparisons were made between the experimental results and density functional theory band structure calculations. Intrinsic electron accumulation near the surface of clean InN was directly observed by ARPES. The accumulation layer is discussed in terms of the bulk Fermi level (E F) lying below the pinned surface E F, with a confining potential formed normal to surface due to the downward band bending facilitated by donor type surface states or nitrogen vacancies. Various spectroscopic techniques were used to measure this band bending. The energy of the Fermi level and the size of the Fermi surface for these quantum well states could be controlled by varying the method of surface preparation and by the adsorption of potassium on the surface. Intermixing between the heavy and light hole valence bands in the intrinsic quantum well potential associated with the surface electron accumulation layer results in an inverted band structure, with the valence band maximum lying away from the Brillouin zone center. Similarly, the electronic band structure of CdO was investigated and quantized electron subbands were observed above the valence band maximum. The origin of the accumulation layer is discussed in terms of the bulk band structure of CdO calculated using quasi particle corrected density functional theory. High electron density at the surface of these materials provides new opportunities for potential device structures such as sensors, high frequency transmitters and field effect transistors. Therefore the study of their near surface electron accumulation and electronic structure is of importance in understanding the properties of these materials and discovering new application areas.
Author: Giorgio Margaritondo Publisher: Springer Science & Business Media ISBN: 9400930739 Category : Science Languages : en Pages : 348
Book Description
E se non che di cid son vere prove A nd were it not for the true evidence Per piti e piti autori, che sa, ra. nno Of many authors who will be Per i miei versi nominati altrove, Mentioned elsewhere in my rhyme Non presterei alla penna 10. mana I would not lend my hand to the pen Per nota1' cid ch'io vidi, can temenza And describe my observations, for fear ehe non fosse do. altri casso e van 0; That they would be rejected and in vane; Mala lor chiara. e vera. esperienza But these authors' clear and true experience Mi assicura. nel dir, come persone Encourages me to report, since they Degne di fede ad ogni gra. n sentenza. Should always be trusted for their word. [From" Dittamondo", by Fazio degli UbertiJ Heterojunction interfaces, the interfaces between different semiconducting materi als, have been extensively explored for over a quarter of a century. The justifica tion for this effort is clear - these interfaces could become the building blocks of lllany novel solid-state devices. Other interfaces involving semiconductors are al ready widely used in technology, These are, for example, metal-semiconductor and insulator-semiconductor junctions and hOll1ojunctions. In comparison, the present applications of heterojunction int. erfaces are limited, but they could potentially becOlne lnuch lllore ext. ensive in the neal' future. The path towards the widespread use of heterojunctions is obstructed by several obstacles
Author: Winfried Mönch Publisher: Springer Science & Business Media ISBN: 9400906579 Category : Science Languages : en Pages : 302
Book Description
Interface and surface science have been important in the development of semicon ductor physics right from the beginning on. Modern device concepts are not only based on p-n junctions, which are interfaces between regions containing different types of dopants, but take advantage of the electronic properties of semiconductor insulator interfaces, heterojunctions between distinct semiconductors, and metal semiconductor contacts. The latter ones stood almost at the very beginning of semi conductor physics at the end of the last century. The rectifying properties of metal-semiconductor contacts were first described by Braun in 1874. A physically correct explanation of unilateral conduction, as this deviation from Ohm's law was called, could not be given at that time. A prerequisite was Wilson's quantum theory of electronic semi-conductors which he published in 1931. A few years later, in 1938, Schottky finally explained the rectification at metal-semiconductor contacts by a space-
Author: Kazuto Akiba Publisher: Springer ISBN: 9811371075 Category : Technology & Engineering Languages : en Pages : 147
Book Description
This book discusses the latest investigations into the electronic structure of narrow-gap semiconductors in extreme conditions, and describes in detail magnetic field and pressure measurements using two high-quality single crystals: black phosphorus (BP) and lead telluride (PbTe). The book presents two significant findings for BP and PbTe. The first is the successful demonstration of the pressure-induced transition from semiconductor to semimetal in the electronic structure of BP using magnetoresistance measurements. The second is the quantitative estimation of how well the Dirac fermion description works for electronic properties in PbTe. The overviews on BP and PbTe from the point of view of material properties help readers quickly understand the typical electronic character of narrow-gap semiconductor materials, which has recently attracted interest in topological features in condensed matter physics. Additionally the introductory review of the principles and methodology allows readers to understand the high magnetic field and pressure experiments.
Author: Winfried Mönch Publisher: Springer Nature ISBN: 3031590643 Category : Condensed matter Languages : en Pages : 156
Book Description
This concise volume examines the characteristic electronic parameters of semiconductor interfaces, namely the barrier heights of metal-semiconductor or Schottky contacts and the valence-band discontinuities of semiconductor-semiconductor interfaces or heterostructures. Both are determined by the same concept, namely the wave-function tails of electron states overlapping a semiconductor band gap directly at the interface. These interface-induced gap states (IFIGS) result from the complex band structure of the corresponding semiconductor. The IFIGS are characterized by two parameters, namely by their branch point, at which their charge character changes from predominantly valence-band- to conduction-band-like, and secondly by the proportionality factor or slope parameter of the corresponding electric-dipole term, which varies in proportion to the difference in the electronegativities of the two solids forming the interface. This IFIGS-and-electronegativity concept consistently and quantitatively explains the experimentally observed barrier heights of Schottky contacts as well as the valence-band offsets of heterostructures. Insulators are treated as wide band-gap semiconductors. In addition, this book: Explains intrinsic interface states of electron states that overlap the band gap of a semiconductor at the interface Includes experimental data on Schottky contacts including carrier height, ideality factor and flat-band barrier height Compares of Theoretical and Experimental Data for a range of semiconductors.
Author: Yue Hao Publisher: CRC Press ISBN: 1315351838 Category : Computers Languages : en Pages : 325
Book Description
This book systematically introduces physical characteristics and implementations of III-nitride wide bandgap semiconductor materials and electronic devices, with an emphasis on high-electron-mobility transistors (HEMTs). The properties of nitride semiconductors make the material very suitable for electronic devices used in microwave power amplification, high-voltage switches, and high-speed digital integrated circuits.
Author: Michel Lannoo Publisher: Springer Science & Business Media ISBN: 3662027143 Category : Science Languages : en Pages : 267
Book Description
Surfaces and interfaces play an increasingly important role in today's solid state devices. In this book the reader is introduced, in a didactic manner, to the essential theoretical aspects of the atomic and electronic structure of surfaces and interfaces. The book does not pretend to give a complete overview of contemporary problems and methods. Instead, the authors strive to provide simple but qualitatively useful arguments that apply to a wide variety of cases. The emphasis of the book is on semiconductor surfaces and interfaces but it also includes a thorough treatment of transition metals, a general discussion of phonon dispersion curves, and examples of large computational calculations. The exercises accompanying every chapter will be of great benefit to the student.
Author: Leyla Colakerol
Author: Leyla Colakerol
Author: Giorgio Margaritondo
Author: Khang Hoang
Author: Winfried Mönch
Author: Kazuto Akiba
Author: Winfried Mönch
Author: Friedhelm Bechstedt
Author: Dat Thanh Do
Author: Yue Hao
Author: Michel Lannoo