Piezoelectric Tunnel FET With a Steep Slope

A design of n-type InAs piezoelectric tunnel FETs (PE-TFETs), which is worth further experimental verification, is proposed for steep sub-thresholdslope and studied using TCAD simulations. Piezoelectric layers (PE-layer) are inserted in gate stacks to induce dynamic compressive strain and to modulate the band gap during switching. The non-equilibrium Green's function (NEGF) approach with strained 8-band k · p Hamiltonian is used to investigate the PE-TFETs performance. Our results suggest that PE-TFETs are compressively strained perpendicular to the transport direction at OFF state, while PE-TFETs feel no strain at ON state. This compressive strain enlarges the channel band gap and meanwhile reduces the tunneling energy window, which greatly suppresses OFF current. In this work, the ntype InAs PE-TFETs achieve 50 times lower OFF current than conventional TFETs, and the minimum SSof PE-TFETs is 48 mV/dec with 0.5 V supply voltage. Moreover, the proposed design is helpful to suppress the ambipolar current.