DIRECT MEASUREMENTS OF ENERGY RELAXATION-TIMES ON AN ALGAAS GAAS HETEROINTERFACE IN THE RANGE 4.2-50 K/

The temperature dependence of the energy relaxation time tau(e)(T) of a two-dimensional electron gas at an A1GaAs/GaAs heterointerface is me asured under quasiequilibrium conditions in the region of the transiti on from scattering by acoustic phonons to scattering with the particip ation of optical phonons. The temperature interval of constant tau(e), where scattering by the deformation potential predominates, is determ ined. In the preceding, low-temperature region, where piezoacoustic an d deformation-potential-induced scattering processes coexist, tau(e) d ecreases slowly with increasing temperature. Optical phonons start to participate in the scattering processes at T similar to 25 K (the char acteristic phonon lifetime was equal to tau(LO)similar to 4.5 ps). The energy losses calculated from the tau(e) data in a model with an effe ctive nonequilibrium electron temperature agree with the published dat a obtained under strong heating conditions. (C) 1996 American Institut e of Physics.