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 angular dependences of the nonequilibrium phonon distribution are studied for interwell transitions and the differences with those for intrawell transitions are pointed out. Due to the interwell interference the energy and angular distributions of the emitted phonons are strongly nonmonotonic. The intensity of the high-energy phonon flow due to interwell transitions is evaluated; for degenerate electrons its value is substantially larger than the intensity of phonon flow caused by the usual process while for nondegenerate hot electrons these two intensities can have comparable values.