Gradient voltage amplification effect in FDSOI NCFET with thickness-variable ferroelectric layer

Abstract

In this paper, a negative capacitance field effect transistor with thickness variable ferroelectric layer (TVFL NCFET) based on the fully depleted silicon on insulator (FDSOI) is proposed. The TVFL NCFET features the linearly increased ferroelectric layer thickness along the channel from source to drain. The gradient voltage amplification effect caused by the TVFL is analyzed according to the proposed capacitance model and simulation. Both of the model and numerical results indicate that the TVFL leads to a gradient increased electrostatic potential distribution along the bottom of the ferroelectric layer. The influences of gradient voltage amplification effect on the transfer characteristics, the output characteristic, the ratio between on-state-current (I ON) and off-state-current (I OFF), the drain induced barrier lowering (DIBL) and the subthreshold swing (SS) are investigated. The results show that the TVFL NCFET achieves the SS of 53.14 mV/dec, which is reduced by 19% when compared to the conventional NCFET. Meanwhile, large ION/IOFF is also realized and up to 1012 at most.