Determination of the Defect Redistribution and Charge Injection Contributions to the a-Si:H Thin-Film Transistor Instability

Abstract

ABSTRACTThe effects of bias-stressing n- and p-channel thin-film transistors, employing thermal silicon dioxide as gate insulator, have been analysed by using different techniques, including field-effect, space-charge photomodulation and photo-induced discharge. Photo-induced discharge experiments have pointed out as parasitic resistance effects can be present in p-channel devices. In order to reduce this problem, thin active layer p-channel devices have been fabricated and, combining these results to those relative to the n-channel transistors, we deduced a predominance of charge injection at low and moderate stress-biases while at high-stress biases modifications in the density of states take place.