Design optimization of vertical nanowire tunneling field-effect transistor based on AlGaSb/InGaAs heterojunction layer

This paper presents the electrical characteristics of vertical nanowire-type tunneling field-effect transistors (VNW TFETs) based on the AlGaSb/InGaAs heterojunction for low-power, high-speed applications. The proposed devices have a very steep junction, based on broken band alignment between the AlGaSb and InGaAs layers. The extremely thin tunneling barrier increases the tunneling probability between the AlGaSb source region and the InGaAs channel region. For this reason, the broken band based on the AlGaSb/InGaAs heterostructure enhances the on-state current (Ion) of the TFETs. To optimize the electrical performance of the proposed device, design optimization using technology computer-aided design (TCAD) simulations is performed. The design variables are gate length, doping concentrations, and the nanowire radius. The optimized device has a gate length of 30 nm, channel and drain doping concentrations of 1018 cm−3, and a radius of 10 nm. Results confirm that the optimized TFET has a subthreshold swing (S) of 27.8 mV/dec and an Ion value of 2.57 mA/μm.