Electrostatically Doped Heterojunction TFET with Enhanced Driving Capabilities for Low Power Applications

This paper projects the enhanced drive current of a ntype electrostatically doped (ED) tunnel field-effect transistor (ED-TFET) based on heterojunction and band-gap engineering via TCAD 2-D device simulations. The homojunction ED-TFET device utilizes the electrostatic doping in order to create the source/drain region on an intrinsic silicon nanowire that also felicitates dynamic re-configurability. The ED-TFET offers good electrostatic control over the channel with reduced thermal budget and process complexity. However, device exhibits low ON current, therefore, in this work, we elaborate on interfacing of group IIIV with group IV semiconductors for heterojunction. Incorporation of heterojunction and band gap engineering in the ED-TFET has improved drive current even at very low operating voltage. The comparison of various low band gap source region materials shows that germanium (Ge) source (Si-Si-Ge) ED-TFET provides steepest subthreshold swing (SS) of about 9.5 mV/dec, and higher ON-state drive current of 1.58 mA at VDS = 1 V and 0.093 mA at VDS = 0.5 V with same SS. Keywords—Tunnel field effect transistor (TFETs), band-to-band tunneling (BTBT), electrostatic doping, heterojunction, band gap engineering, TCAD.