Mitigating Tunneling Leakage in Ultrascaled HfS2 pMOS Devices With Uniaxial Strain

Abstract

Monolayer HfS2 is promising for an all-2D CMOS platform due to its well-balanced n- and p-type transport properties, and is predicted to show high drive currents into the sub-10-nm channel length regime. However, the OFF-state performance of the ultrascaled HfS2 pMOS device is limited by direct source-drain tunneling (SDT) due to carriers in the degenerate light-hole band. Here we use full-band quantum transport simulations to show that this effect can be mitigated through the use of uniaxial tensile strain, which splits the degeneracy of the valence bands and tunes the effective mass in the transport direction to suppress SDT. Strain of 1-2% applied in the transport direction reduces the subthreshold swing by over 20 mV/dec, which can improve the ON current by over 50% at channel lengths below 7 nm. This approach can be further used to tune the HfS2 pMOS device to match the nMOS characteristics at a similar channel length.