BIAS LIGHT-INDUCED DEFECT RELAXATION PHENOMENA IN HYDROGENATED AMORPHOUS-SILICON

Modulated photocurrent (MPC) measurements of intrinsic n-Si:H have dis closed a defect band of electron trapping states whose thermal emissio n rate shifts in response to applied bias light. This shift has been m easured both as a function of light intensity and in a transient mode as the light is switched on and off. The motion of this band is found to be intimately related to the changes in the photoconductivity and, in particular, to the phenomenon of the long-time photoconductivity de cay in a-Si:H. Similar shifts have also been observed in the sub-band- gap optical spectra of the defect transitions. An analysis based upon a defect distribution produced by relaxation dynamics is found to accu rately reproduce our observations.