Energy-level dynamics of deep gap states in hydrogenated amorphous silicon under illumination

Abstract
Relaxation dynamics of deep defects, recently observed in modulated photocurrent and electron drift measurements, are explained in terms of random temporal fluctuations of localized-state energies. The fluctuations can be caused by a randomly changing microscopic configuration of excess charge carriers or by carrier annihilation processes. A model is developed which leads to dependences of the thermal emission energy upon temperature and optical bias, in good agreement with existing experimental data. © 1996 The American Physical Society.