Abstract
The field-effect conductance of hydrogenated amorphous silicon thin-film transistors has been calculated as a function of the gate voltage. This analysis differs from the existing ones in taking into account (1) the space charge due to excess free carriers, in addition to that caused by modulation of bulk localized state occupancy, and (2) the charge in the surface states in the determination of the boundary condition. Numerical results are presented to demonstrate the significance of these effects.