Electron velocity overshoot at room and liquid nitrogen temperatures in silicon inversion layers

摘要

Effective electron velocities in silicon MOSFETs exceeding the bulk saturation values of 10/sup 7/ cm/s at room temperature and 1.3*10/sup 7/ cm/s at liquid-nitrogen temperature are inferred. This conclusion suggests that electron velocity overshoot occurs over a large portion of the device channel length. To infer this phenomenon, submicrometer-channel-length Si MOSFETs with lightly doped inversion layers were fabricated. These devices have low field mobility of 450 cm/sup 2//V-s and showed only slight short-channel effects. Effective carrier velocities are calculated from the saturated transconductance g/sub m/ at V/sub DS/=1.5 V after correction for parasitic resistances of source and drain.