EMISSION OF ACOUSTIC PHONONS DUE TO TUNNEL RELAXATION OF NONEQUILIBRIUM ELECTRONS IN DOUBLE-QUANTUM WELLS

Emission of nonequilibrium acoustic phonons due to electron tunneling in double-quantum-well structures is considered. The energy and angula r dependences of the nonequilibrium phonon distribution are studied fo r interwell transitions and the differences with those for intrawell t ransitions are pointed out. Due to the interwell interference the ener gy and angular distributions of the emitted phonons are strongly nonmo notonic. The intensity of the high-energy phonon flow due to interwell transitions is evaluated; for degenerate electrons its value is subst antially larger than the intensity of phonon flow caused by the usual process while for nondegenerate hot electrons these two intensities ca n have comparable values.