Optical Absorption Probability for the Zone-Folding Induced Quasi-Direct Gap in Ge(x)Si(1−x)/Si Strained Layer Superlattices

Abstract

AbstractUsing a realistic zone-folding scheme for a Ge(x)Si(1−x)/Si strained layer superlattice having a Si-like conduction band structure (i.e ≲85% Ge) we calculate the transition probability for the zone-folding induced direct optical gap and compare it with the indirect band gap absorption probability. The results suggest that such zone-folding induced direct optical transitions are promising for optical devices made from Ge(x)Si(1−x)/Si strained layer superlattices and like structures, provided they are fabricated in such a way that the appropriate zone-folding occurs.