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.