Energy resolved spin-polarised electron photoemission from strained GaAs/GaAsP heterostructure

High resolution energy distribution curves (EDC) and a polarisation versus energy distribution curves (PEDC) of the electrons, photoemitted from strained GaAs/GaAsP layers are experimentally studied. The basic structures of the spectra are found to vary with temperature and illuminating wavelength. The ageing of the activation layer changes the EDC shape as well. Nevertheless, in the vicinity of the photoexcitation threshold the polarisation does not vary across the energy distribution both at room and 120 K temperatures of the cathode, which means that no depolarisation occurs during energy relaxation in the band bending region. The electron energy distribution is interpreted in terms of the electron energy relaxation in the band tail states of the quantum well formed by the band-bending region.