Electron-hole Scattering in GaAs Quantum Wells.

Momentum and energy relaxation of minority carriers in GaAs quantum wells is studied in a series of experiments. At low temperatures electron-hole scattering is the dominant scattering mechanism for minority carriers in high quality samples, causing dramatic carrier-drag effects (e.g., negative drift or negative absolute mobility) in the minority carrier transport. Quantitative analysis of all-optical drift-velocity measurements shows that the momentum relaxation times of minority electrons in a hole plasma are much shorter (40 to 100 fs) than those of minority holes in an electron plasma (2 - 5 ps).