Contact resistance in Schottky contact gated-four-probe a-Si thin-film transistor

The source and drain electrode contact resistance of the hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) with a Schottky-barrier source/drain contact was measured using a gated-four-probe TFT structure. Typically its variation with the gate bias is considered to be independent of the gate bias but we observed that contact resistances decrease exponentially with increasing gate bias. Our experimental data are explained by a combination of the tunneling current through the Schottky barrier and the access source/drain contact TFT resistance.