The effects of doping, gate length, and gate dielectric on inverse subthreshold slope and on/off current ratio of a top gate silicon nanowire transistor

Abstract

The effects of gate length Lg, gate dielectric constant isinox, gate oxide thickness tox, and sourc/drain doping concentration on inverse subthreshold slope and on/off current ratio of a top gate silicon nanowire on insulator device are studied using three dimensional quantum simulation. The variation of inverse subthreshold slope and on/off current ratio are very sensitive to gate length, gate dielectric constant, and oxide thickness and relatively less sensitive to doping concentration. Significant improvement in subthreshold slope and on/off current ratio can be achieved using high-K gate dielectric with thinner oxide and relatively longer gate. The key feature of this improvement is the better gate control of channel potential with longer Lg, higher isinox, and thinner tox. Due to better control of channel potential, the tunneling current through the conduction band is significantly suppressed in the subthreshold regime that improves the subthreshold slope and on/off current ratio.