Field effect on electron-hole recombination in Si/Si 1− xGe x/Si quantum wells having a W-like type II potential profile

Abstract

A theoretical analysis, using a Schrödinger solver, is made to calculate the electric field-dependent interband transitions in a Si/Si 1− x Ge x /Si double QW strain-compensated in relaxed Si 1− y Ge y barriers. The conduction and the valence band present a W-like potential profile, resulting in a quasi-type I heterostructure. Three peculiar features are revealed as the electric field is increased: (i) two uncoupled e 11 and e 12 electron levels are generated, (ii) the e 11–hh 1 fundamental transition due to first silicon QW exhibits a red shift in emission energy while the e 12–hh 1 transition energy is bleu shifted, (iii) an improved wave function overlap for the e 11–h 1 fundamental transition, the latter property showing the advantage having two adjacent QWs in this W architecture.