Physics and applications of Ge_xSi_1-x/Si strained-layer heterostructures

Abstract

This paper reviews recent advances in our current level of understanding of the physics underlying transport and optical properties of Ge <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Si <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> /Si strained-layer heterostructures. Included are discussions of critical (maximum) layer thicknesses, effects of coherency strain on the bandgaps of both Si and Ge <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Si <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> and the influence of layer strains on the band alignments of Ge <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Si <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> /Si strained-layer heterostructures. Transport studies will center on the modulation doping results of both n and p type heterostructures. Indeed, these earlier transport studies provided essential information which led to an understanding of the band-alignment in these strained layer heterostructures. Recent measurements of the indirect bandgap of Ge <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> Si <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> strained layers on