Direct determination of impact-ionization rates near threshold in semiconductors using soft-x-ray photoemission

Abstract

The line shape of the Al 2p core-level photoemission peak in Al0.9Ga0.1As is found to be strongly dependent on the electron kinetic energy. Using Monte Carlo transport simulations it is shown that the observed strong, asymmetric line broadening is caused by electron-phonon scattering. In agreement with the experimental observation, the simulations predict that this phonon-induced line broadening is rapidly suppressed as the core line is shifted through the impact-ionization threshold. Thus, it becomes possible to infer from the core-level line shape the energy-dependent impact-ionization rates near the impact-ionization threshold. © 1992 The American Physical Society.