QUANTUM AND CLASSICAL LIFETIMES IN A GA0.49IN0.51P/GAAS HETEROJUNCTION

We report a study of the subband structure of Ga0.49In0.51P/GaAs heterojunctions. High-field (O < B < 20 T) magnetotransport measurements were performed at low temperatures (4.2 K) under hydrostatic pressure (P < 12 kbar). The strong persistent photoconductivity effect in this system allowed us to tune the two-dimensional electron gas (2DEG) density (N2D) with short light bursts from a red electroluminescent diode. The pressure dependence of N2D shows that in contrast with other systems, pressure effects on the band discontinuity and the effective mass are responsible for the observed density dependence. Both single particle (quantum) and scattering (classical) lifetimes were measured. The ratio of the classical-to-quantum lifetimes was large (almost-equal-to 10) at ambient pressure and confirmed the dominant role of scattering by remote ionized impurities. After illumination, the ratio quickly decreases with increasing 2DEG density. However when pressure is applied, this ratio decreases with decreasing N2D, giving evidence of a pressure-induced misfit strain at the interface that modifies the dominant scattering mechanisms.