ENERGY RELAXATION OF HOT-ELECTRONS IN GAAS ALGAAS SUPERLATTICES MEASURED BY INFRARED DIFFERENTIAL SPECTROSCOPY/

The energy relaxation of hot electrons in a strongly coupled, n-type G aAs/AlGaAs superlattice is measured by analysing the temperature and e lectric-field dependence of the interminiband absorption. Electrons ar e heated up by an electric-field pulse and the resulting change of the electron temperature is measured by monitoring the spectral change of the infrared absorption. The measured energy-loss rates are higher th an predicted by a simple 3D model including acoustic and LO phonon emi ssion. Other possible relaxation channels, such as folded acoustic pho nons or coupled plasmon-phonon modes are discussed. An energy relaxati on time can be extracted from the power balance and results to vary be tween 300 ps at 15 K and 20 ps at 48 K. (C) 1997 Academic Press Limite d