Subthreshold model of a polycrystalline silicon thin-film field-effect transistor

A model is presented for the subthreshold current versus gate voltage of a polycrystalline silicon thin-film field-effect transistor. It utilizes the experimentally observed exponential density of states of polycrystalline silicon grain boundaries and is based on an earlier model of M. Shur and M. Hack [J. Appl. Phys. 55, 3831 (1984)] which they applied to hydrogenated amorphous silicon. Experimental subthreshold curves are presented along with the corresponding curves predicted by the model. In addition current activation data are shown to fit the model. The primary fitting parameter is the density of states at the valence band.