Near band-edge luminescence of semi-insulating undoped gallium arsenide at high levels of excitation

The dependences of the maximum and the half-width of near band-edge photoluminescence of semi-insulating undoped-GaAs crystals at 77 K on the concentration of background acceptor impurities and the level of excitation in the range from 3×1021 to 6×1022 quantum/(cm2 s) are investigated. The observed dependences are explained by formation of the density tails of states as a result of fluctuations of impurity concentration and participation of localized states of the donor impurity band in radiative transitions. Reduction of many-particle interaction at increasing of N can be connected with increasing of shielding of charge carriers by atoms of impurity.