Many-body and hot-phonon effects in the radiative emission spectrum of CdS under high excitation intensities

Abstract

We present here experimental results concerning the photoluminescence spectrum of CdS under high excitation intensities. With increasing excitation intensity the single emission band observed at 77 \ifmmode^\circ\else\textdegree\fi{}K shows a peak displacement towards lower energies, and enhancement of its low-energy side as well as of its high-energy side. These effects increase with excitation intensity. We develop a complete model that can account for the above behavior and the emission band shape. The broadening is mainly due to nonequilibrium distribution of LO phonons, though contributions to the high-energy side from hot electrons is quite significant. Self-energy corrections account for the band reduction and consequently to the shift of the luminescence band peak towards lower energies.