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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Optical properties in inhomogeneous layered media with special reference to ion-implanted semiconductors

12 February 2015 (has links)
D.Ing. (Electrical and Electronic Engineering) / A theory was developed for the investigation of the optical properties of inhomogeneous layered media. Reflectivity and transmissivity analysis of multi-layered structures was realized by utilizing flow graph representations and by employing Mason's rule. This study served as a base for the development of analytical expressions in integral form for reflectivity, transmissivity, reflectance, bilinear transformed reflectance and transmittance of materials possessing inhomogeneous refractive index profiles. These proposed formulas were derived for both normal and oblique incidence and contemplate nonabsorbing, as well as, absorbing materials. An ellipsometric expression for inhomogeneous layers was also derived by employing the developed theory. Several hypothetical examples that emulate refractive index profiles in ionimplanted semiconductors were investigated, including a buried layer with a gaussian refractive index profile, and two homogeneous layers with a half-gaussian transition region between them. Curves of reflectance versus wave number were simulated using the derived formulations in two different ways: (i) employing numerical methods (ii) applying analytical solutions. The performance of these simulations was compared to standard techniques such as the matrix method and the Wentzel-Kramers-Brillouin (WKB) approximation. Very good agreement between the proposed theory and the matrix technique was found. The developed formulations were appropriate even at wave numbers where the WKB approximation was not valid. It must be stressed that the analysis of the reflectance at these wave numbers is important in the study of processed semiconductors. In comparison to the matrix technique, the integral formulation led to substantial time saving, which, depending on the particular application, was between one and two orders of magnitude faster. This fact indicated that the developed expressions for reflectance and transmittance can be used to great advantage in least-square curve-fit ...
32

Damage enhanced diffusion of impurities in semiconductors.

January 1991 (has links)
by Lo Veng Cheong. / Parallel title in Chinese characters. / Thesis (Ph.D.) -- Chinese University of Hong Kong, 1991. / Bibliography: leaves 116-119. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / LIST OF SYMBOLS --- p.iv / LIST OF FIGURES --- p.ix / LIST OF TABLES --- p.xii / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter CHAPTER TWO --- SURVEYS ON THEORETICAL MODELS --- p.7 / Chapter 2.1 --- Some Basic Concepts --- p.7 / Chapter 2.1.1 --- Vacancy Mechanism and Interstitial Mechanism --- p.7 / Chapter 2.1.2 --- Relative Contribution from Various Point Defects Species --- p.15 / Chapter 2.1.3 --- Impurity Point Defect Pairs or 'Centers' --- p.20 / Chapter 2.1.4 --- Anomalous Diffusion --- p.21 / Chapter 2.2 --- Historical Review on Theoretical Models --- p.22 / Chapter 2.3 --- Formulation of the General Model --- p.29 / Chapter 2.3.1 --- Effects to be and Not to be Considered --- p.30 / Chapter 2.3.2 --- Derivation of the Basic Equations --- p.31 / Chapter CHAPTER THREE --- MODELING OF THE DAMAGE ENHANCED DIFFUSION OF IMPLANTED BORONS IN SILICON --- p.35 / Chapter 3.1 --- Brief Description of Powell's Experiment --- p.35 / Chapter 3.2 --- Modeling --- p.38 / Chapter 3.3 --- Results and Discussion --- p.45 / Chapter CHAPTER FOUR --- EXPERIMENTAL INVESTIGATION OF BORON DIFFUSION DIFFUSION ASSISTED BY THE NON-UNIFORMITY OF POINT DEFECTS --- p.66 / Chapter 4.1 --- Introduction --- p.66 / Chapter 4.2 --- Experimental --- p.67 / Chapter 4.3 --- Results and Discussion --- p.88 / Chapter CHAPTER FIVE --- CONCLUSION AND FURTHER SUGGESTIONS --- p.103 / Chapter 5.1 --- Conclusion --- p.103 / Chapter 5.2 --- Further Suggestions --- p.104 / Chapter APPENDIX A --- DOPANT CONCENTRATION DEPENDENCE OF THE ENHANCED DIFFUSION --- p.107 / Chapter APPENDIX B --- FLOW CHART OF NUMERICAL SIMULATION --- p.111 / REFERENCE --- p.116
33

Advanced simulation of wide band gap semiconductor devices

Farahmand, Maziar 08 1900 (has links)
No description available.
34

Computation of conductance for ballistic nanostructures

Martin, Shashi A. January 1994 (has links)
Future electronic devices having dimensions on the nanometer scale will rely on the resultant quantum effects for their operation. In this project, these quantum effects were investigated through the theoretical modeling and computer simulation of a confined twodimensional electron gas in a semiconductor heterostructure. Assuming hardwall boundaries and sharp geometrical features, the nanostructure conductance has been calculated by finding transverse eigenvalues and eigenfunctions, computing hopping integrals for a one-dimensional tight binding lattice, determining the Greens' propagators, and then finally evaluating the transmittance. From the transmittance, the conductance was determined.A structured and modular computer program in FORTRAN was developed to investigate the effects of geometrical modifications on the conductance of ballistic nanochannels. The program has been designed in such a way that the user need only supply the nanostructure specifications to an input data file. The program then uses this data file to perform the calculations. A separate, user-friendly program has been developed to form the data file. The program is such that additions and modifications can be easily made in the future. / Department of Physics and Astronomy
35

Simulation of defect nucleation with low energy amorphizing silicon and germanium implants

Bellarmine, P. Xavier. January 2004 (has links)
Thesis (M.S.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 132 pages. Includes vita. Includes bibliographical references.
36

Optical characterization of compound semiconductors using photoconductivity and photoreflectance

Stoica, Vladimir A. January 2000 (has links)
Thesis (M.S.)--West Virginia University, 2000. / Title from document title page. Document formatted into pages; contains iv, 68 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 67-68).
37

Electrical characterization of n-type aluminum gallium arsenide

Kim, Seung-bae 11 July 1991 (has links)
Graduation date: 1992
38

Spin-dependent transport in magnetic tunnel junctions and diluted magnetic semiconductors

Wang, Weigang. January 2009 (has links)
Thesis (Ph.D.)--University of Delaware, 2008. / Principal faculty advisor: John Q. Xiao, Dept. of Physics and Astronomy. Includes bibliographical references.
39

Study of grown-in defects and radiation-induced defects in GaAs and AlxGa1?xAs

Wang, Weng-Lyang, January 1984 (has links)
Thesis (Ph. D.)--University of Florida, 1984. / Description based on print version record. Typescript. In "AlxGa₁₋xAs" in title, "x" is subscript. Vita. Includes bibliographical references (leaves 182-189).
40

Multiple photonic response in organic-based magnetic semiconductor

Yoo, Jung-Woo. January 2007 (has links)
Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

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