Observation of Electron Velocity Overshoot in Sub-100-nm-Channel MOSFET's in Silicon

摘要

N-channel MOSFET's with channel lengths from 75 nm to 5 micron were fabricated in Si using combined X-ray and optical lithographies, and were characterized at 300, 77, and 4.2 K. Average channel electron velocities ve were extracted according to the equations ve = gmi/Cox, were gmi is the intrinsic transconductance and Cox is the capacitance of the gate oxide. We found that at 4.2 K the average electron velocity of a 75-nm-channel MOSFET is 1.7 X 10 to the 7th power cm/s, which is 1.8 times higher than the inversion layer saturation velocity reported in the literature, and 1.3 times higher than the saturation velocity in bulk Si at 4.2 K. As channel length increases, the average electron velocity drops sharply below the saturation velocity in bulk Si. These experimental results strongly suggest velocity overshoot in a 75-nm-channel MOSFET. (Reprints)