Study of Electron Velocity Overshoot in NMOS Inversion Layers

Non-local electron transport in nMOSFET inversion layers has been studied by MonteCarlo (MC) simulations. Inversion layer quantization has been explicitly included in thecalculation of density of states and scattering rate for low-energy electrons while bulkband structure is used to describe the transport of more energetic electrons. Foruniform, high-lateral field conditions, the effects of quantization are less pronounceddue to the depopulation of electrons in the lower-lying subbands. On the other hand,Monte Carlo results for carrier transport in spatially varying lateral fields (such as thosein the inversion layer of MOSFETs) clearly indicate that depopulation of the low-lyingsubbands is less evident in the non-local transport regime. Quasi-2D simulations haveshown that, at high transverse effective field, the inclusion of a quantization domaindoes have an impact on the calculated spatial velocity transient