PHONON EMISSION BY HOT 2D ELECTRONS AND HOLES IN A GALLIUM-ARSENIDE HETEROJUNCTION - THE INFLUENCE OF SCREENING AND ACOUSTIC ANISOTROPY

The process of energy relaxation by phonon emission of hot two-dimensi onal electrons and holes in GaAs/AlGaAs heterojunctions has been studi ed using the heat-pulse technique for carrier temperatures below 40 K. To explain the experimental findings and to understand fully the proc ess of electron- (or hole-) phonon coupling, theoretical calculations of the angular and polarization dependence of the emitted acoustic pho nons were made. Phonon emission studies give detailed information conc erning the phonon wave vector and polarization dependence of the emiss ion process. This allows, in connection with the corresponding numeric al simulations, interesting conclusions regarding the properties of th e 2D carrier system itself (e.g. strength of carrier-phonon coupling c onstants, confinement of the 2D carriers perpendicular to the 2D syste m) to be reached. (C) 1998 Elsevier Science B.V. All rights reserved.