Single-particle relaxation time of the two-dimensional electron gas in Si/SiGe: many-body effects

The single-particle relaxation time of the two-dimensional electron gas in SiGe/Si/SiGe quantum wells is calculated. Many-body effects beyond the random-phase approximation become important at low electron density. For charged impurity scattering (remote doped) we analyze the importance of these many-body effects as function of the electron density and the spacer width. Induced by many-body effects a strong reduction of the single-particle relaxation time at low electron density is predicted. We describe the relation with the transport scattering time, we comment on multiple-scattering effects and we discuss the determination of many-body effects in existing samples.