The relaxation dynamics of deep defects which had been detected using modulated photo-current and electron drift measurements were explained in terms of random temporal fluctuations of localized-state energies. It was suggested that the fluctuations could be caused by a randomly changing microscopic configuration of excess charge carriers, or by carrier annihilation processes. A model was developed which reproduced the observed dependence of the thermal emission energy upon temperature and optical bias.

V.I.Arkhipov, G.J.Adriaenssens: Physical Review B, 1996, 54[23], 16696-700