Optimum top and bottom oxide thicknesses and flat-band voltages for improving subthreshold characteristics of 5Â nm DGMOSFET

This paper has proposed the optimum design rules as investigating subthreshold characteristics of 5 nm DG (Double Gate) MOSFET for top/bottom gate flat-band voltages and oxide thicknesses. The difference of top gate voltages between on-current (10−7A) and off-current (10−12A) is specified as ΔVon−off, and the top-gate voltage for the on-current is defined as the threshold voltage. ΔVon−off and the threshold voltage are derived from equations for the drain current and gate voltage for various top/bottom gate flat-band voltages and oxide thicknesses, and compared with those for symmetric structure having equal top/bottom gate flat-band voltages and oxide thicknesses. As a result, the potential distributions for top/bottom gate flat-band voltages and oxide thicknesses influence on directly the tunneling current, which greatly changes ΔVon−off and the threshold voltage in subthreshold region. It is established that the top flat-band voltage and oxide thickness have to be larger than the bottom flat-band voltage and oxide thickness to reduce ΔVon−off and threshold voltage, compared with those of symmetric structure.