Increased Subthreshold Current due to Source–Drain Direct Tunneling in Ultrashort-Channel III–V Metal–Oxide–Semiconductor Field-Effect Transistors

The influence of quantum transport effects in ultrashort-channel InP metal–oxide–semiconductor field-effect transistors (MOSFETs) was investigated using a Wigner Monte Carlo method, in which both quantum transport and carrier scattering effects can be fully incorporated. It was found that source–drain (SD) direct tunneling becomes evident for channel lengths of less than about 20 nm. Since this critical channel length is approximately three times larger than that in Si-MOSFETs, countermeasures should be taken to suppress SD direct tunneling in order to aggressively downscale III–V channel MOSFETs. In contrast, quantum reflection effects were found to have a negligible influence on the on-state drain current.