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.