Secondary emission studies of hot carrier relaxation in polar semiconductors

The details of the initial relaxation of optically injected hot carriers in polar semiconductors are studied by Raman scattering from nonequilibrium LO phonons and anti-Stokes hot luminescence. Experiments on intrinsic and doped GaAs reveal carrier-phonon and carrier-carrier interaction times, the wavevector dependence of the hot phonon distribution, and the influence of holes on the LO phonon lifetime. Studies in AlxGa1-xAs probe the influence of alloy disorder on the generation of hot phonons. In addition, because there are two optic phonon modes in AlxGa1-xAs, we can experimentally measure the effect of ionicity (the frequency difference between LO and TO phonons) on the generation rate for the hot phonons. © 1988.