Field effect on electron-hole recombination in Si/Si1−xGex/Si quantum wells having a W-like type II potential profile

A theoretical analysis, using a Schrödinger solver, is made to calculate the electric field-dependent interband transitions in a Si/Si1−xGex/Si double QW strain-compensated in relaxed Si1−yGey 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 e11 and e12 electron levels are generated, (ii) the e11-hh1 fundamental transition due to first silicon QW exhibits a red shift in emission energy while the e12-hh1 transition energy is bleu shifted, (iii) an improved wave function overlap for the e11-h1 fundamental transition, the latter property showing the advantage having two adjacent QWs in this W architecture.