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Title:Growth mechanisms and electronic structure of epitaxial (III-V)(1-x)(IV(2))(x) metastable semiconductors
Author(s):Fons, Paul James
Doctoral Committee Chair(s):Greene, Joseph E.
Department / Program:Physics, Condensed Matter
Engineering, Materials Science
Discipline:Physics, Condensed Matter
Engineering, Materials Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Condensed Matter
Engineering, Materials Science
Abstract:Single-crystal metastable (III-V)$\sb{\rm 1-x}$(IV)$\sb{\rm x}$ alloys are a new class of semiconductors with the potential, through bandgap engineering, of extending the range of achievable electronic and optical properties available for device design. In addition, metastable (III-V)$\rm \sb{1-x}(IV\sb2)\sb{x}$ semiconducting alloys exhibit unusual long and short range ordering behavior. Although maximum mutual equilibrium solid solubilities for $\rm (GaSb)\sb{1-x}(Ge\sb2)\sb{x}$, $\rm (GaAs)\sb{1-x}(Ge\sb2)\sb{x}$, and $\rm (GaAs)\sb{1-x}(Si\sb2)\sb{x}$ are typically less than 4 at.%, recent developments in ion-surface interaction assisted growth techniques have made it possible to grow alloys ranging throughout the pseudobinary composition diagram. A common characteristic of the (100) oriented (III-V)$\rm \sb{1-x}(IV)\sb{x}$ alloys studied in this work--(GaAs)$\sb{\rm 1-x}$(Ge$\sb2)\sb{\rm x}$, $\rm (GaSb)\sb{1-x}(Ge\sb2)\sb{x}$ and $\rm (GaAs)\sb{1-x}(Si\sb2)\sb{x}$--is that for low x values, they exhibit long-range zincblende order, while for x above a critical value, x$\sb{\rm c}$, they exhibit long-range diamond order. While several metastable (III-V)$\rm \sb{1-x}(IV)\sb{x}$ alloys have been grown and characterized, there still exists no general understanding of this new class of materials. In this work, an energy dependent Monte-Carlo kinetic growth model is developed that simulates the growth of these alloys in a layer-by-layer process. The effects of variations in pair-interaction energies and growth conditions on both structural and electronic properties of the alloys is investigated using the bond-energy kinetic growth model in conjunction with Haydock recursion calculations, a Green's function technique for computation of the valence band density-of-states. The results of these models are compared with experimental results and are used to explain the observed changes in critical composition and other ordering properties among the (III-V)$\rm \sb{1-x}(IV\sb2)\sb{x}$ alloys.
Issue Date:1990
Rights Information:Copyright 1990 Fons, Paul James
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9114237
OCLC Identifier:(UMI)AAI9114237

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