Induced electrostatic confinement of electron gas in W-designed strain-compensated Si/Si1–xGex/Si type-II quantum wells

We present a numerical modeling of the conduction- and the valence-band diagrams of W designed Si/Si0.4Ge0.6/Si type II quantum wells. These W structures, strain-compensated on relaxed Si0.75Ge0.25 pseudo-substrates, are potentially interesting for emission and photo-detection around a 1.55μm wavelength. Two main features have been extrapolated by solving self-consistently Schrödinger and Poisson equations, taking into account the electrostatic attraction induced by carrier injection: (i) Coulomb attraction strongly modifies the band profiles and increases the electron probability density at the quantum well interfaces. (ii) The injected carrier concentration enhances the in-plane oscillator strength and the electron–hole wave-function overlap.