Comprehensive Study of Quasi-Ballistic Transport in High- $\kappa$ /Metal Gate nMOSFETs

We study quasi-ballistic transport in nanoscale high-κ/metal gate nMOSFETs based on radio-frequency (RF) S-parameter analysis. An RF S-parameter-based simple experimental methodology is used for direct extraction of device parameters (i.e., L_eff, R_sd, and C_inv) and the effective carrier velocity v_eff from the targeted short-channel devices. Furthermore, an analytical top-of-the-barrier model, which self-consistently solves the Schrödinger-Poisson equations, is used to determine the ballistic carrier velocity v_inj at the top of the barrier near the source. Based on the results of the experimental extraction and analytical calculations, backscattering coefficient r_sat and ballistic ratio BR_sat are calculated to assess the degree of the transport ballisticity for nMOSFETs. It is found that conventional high-κ/metal gate nMOSFETs will approach a ballistic limit at an effective gate length L_eff of approximately 7 nm.