Extraction of quasi-ballistic transport parameters in Si double-gate MOSFETs based on Monte Carlo method

In this study, we have developed an evaluation tool of quasi-ballistic transport parameters in realistic devices, to clarify practical benefits of downscaling MOSFETs into ultimate physical scaling limit. It is found that ballistic transport in double-gate (DG) MOSFETs is enhanced due to the channel length (Lch) scaling until Lch = 10 nm, but when Lch is further scaled to less than 10 nm using TSi = Lch/3 scaling rule, where TSi is the channel thickness, surface roughness scattering intensified by spatial fluctuation of quantized subbands drastically degrades ballistic transport. Furthermore, on-current increase or decrease of ultra-scaled DG MOSFETs is found to be basically determined by a backscattering coefficient R. Gate and drain bias voltage dependencies of ballisticity are also evaluated.