Velocity overshoot in ultrathin double-gate silicon-on-insulator transistors

Abstract

Concerning electron velocity overshoot in ultrathin double-gate silicon-on-insulator transistors, as a function of the silicon thickness and the electron sheet density, it is proved that for very small silicon thicknesses (smaller than 5 nm), velocity overshoot behavior is dominated by the average conduction effective mass; that is, the lower the average conduction effective mass, the higher the velocity overshoot peak. Thus, the velocity overshoot peak increases as the silicon thickness decreases, unlike low-field electron mobility, which diminishes abruptly at silicon thicknesses below 5 nm. This fact enables further reduction in the device channel length, in contrast to what might be supposed from the low-field mobility behavior.