Exciton energy relaxation on acoustic phonons in double-quantum-well structures

The paper analyzes the rate of energy relaxation involving acoustic phonon emission between exciton states in a double quantum well. A theoretical stu dy is made of the part played by two mechanisms, one of which is a one-step transition with emission of an acoustic phonon and the other is a two-step transition, which includes elastic exciton scattering from interface nonun iformities followed by energy relaxation within an exciton subband. The rat e of the two-step transition in real double quantum wells is shown to be hi gher than that of the one-step transition. As follows from calculations, th e fast energy relaxation between exciton states is determined by the elasti c scattering of phonons from the interface.