Understanding negative differential resistance and region of operation in undoped HfO2-based negative capacitance field effect transistor

Abstract

In this paper, we have discussed, negative differential resistance and region of operation in Negative Capacitance Field Effect Transistor. NDR occurs in drain characteristics because of coupling between drain voltage and internal gate voltage via gate to drain capacitance. NDR is more pronounced in NCFET at low gate bias and higher ferroelectric thickness. At these conditions internal voltage starts decreasing with increase in drain bias which is responsible for non-saturation or decrease in drain current with positive incremental change in drain bias which is termed as NDR. NDR in drain characteristics also leads to negative output conductance in NCFET. Negative value of output conductance occurs because of negative drain coupling factor in NCFET. Negative value of drain coupling factor is a necessary condition for hysteresis free operation. Also Gummel Symmetry Test has been done to validate the model. Further we have discussed about region of operation in NCFET and resistive load inverter based on NCFET.