Polarization of hot-electron photoluminescence in GaAs-type semiconductors for recombination on a shallow acceptor.

Abstract

We study the degree of circular polarization ${P}_{c}$ of the hot luminescence, for a circularly polarized excitation, as a function of the energy \ensuremath{\varepsilon} of the electron in the conduction band. Schechter's variational wave functions are used for the acceptor ground state. The band wave functions are treated within a spherical approximation, including a mixing of the light-hole valence band with the spin-orbit split-off band. We find that ${P}_{c}$, for excitation from the heavy-hole valence band, rises rapidly from (1/4) as \ensuremath{\varepsilon} increases from 0, and then gradually saturates towards the value (5/7). This accounts for the increase of ${P}_{c}$ value at the high-frequency edge with increasing excitation energy ${E}_{\mathrm{ex}}$, in the low ${E}_{\mathrm{ex}}$ range, observed recently in GaAs and also in the direct-gap luminescence in ${\mathrm{GaAs}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{P}}_{\mathrm{x}}$ alloys.