ELECTRIC-FIELD EFFECTS ON HOT-ELECTRON LUMINESCENCE FROM P-GAAS

Photoelectrons in the conduction band of GaAs have energy, momentum an d spin distributions determined by the anisotropic valence band struct ure and the optical matrix elements. In p-type GaAs, a small fraction recombine with acceptor states, producing a Hot Electron Luminescence (HEL) spectrum with a series of peaks due to discrete energy losses th rough LO-phonon emission. The highest peak has an energy structure due to warping of the initial heavy hole (HH) band. We report measurement s of its lineshape and polarisation, identifying emission from electro ns along particular k-directions. An electric field of 1 kV cm(-1) dis torts the momentum distribution, and this is reflected in the polarisa tion profiles. The lineshapes and profiles are modelled using a k.p ba nd structure and optical matrix elements, the effect of the field bein g included using a k-broadening model.