Channel length scaling limits of III–V channel MOSFETs governed by source–drain direct tunneling

The difference in the impact of source–drain (SD) direct tunneling in In0.53Ga0.47As and InP metal–oxide–semiconductor field-effect transistors (MOSFETs) was investigated by a quantum Wigner Monte Carlo simulation. It was found that the subthreshold current increase due to SD direct tunneling is more marked in In0.53Ga0.47As MOSFETs owing to their lower effective mass. In addition, the critical channel length at which a drastic increase in subthreshold current occurs owing to SD direct tunneling was found to be about 20 nm for both In0.53Ga0.47As and InP MOSFETs. Since this value is significantly larger than that for Si MOSFETs, SD direct tunneling can be a major obstacle in downscaling III–V MOSFETs into L ch < 20 nm. Hence, to go beyond the end of the roadmap, we will need a selection of materials to suppress SD direct tunneling.