Mobility and metal–insulator transition of the two-dimensional electron gas in SiGe/Si/SiGe quantum wells

We consider the mobility of the interacting two-dimensional electron gas as realized in SiGe/Si/SiGe quantum wells. For zero temperature we calculate the mobility as function of the electron density for remote charged-impurity scattering and we take into account exchange-correlation effects and multiple-scattering effects. Multiple-scattering effects give rise to a metal–insulator transition at low electron density. Our calculation is in good agreement with experimental results obtained with remote doped SiGe/Si/SiGe quantum wells having electron densities near the metal–insulator transition. We discuss the critical density of the metal–insulator transition as function of the remote doping distance and make some predictions. The single-particle relaxation time and spin-polarization effects are also considered.