On the Mean Free Path for Backscattering in $k_{B}T$ Layer of Bulk Nano-MOSFETs

We perform Monte Carlo particle simulations on a silicon conductor for the purposes of reexamining the channel backscattering in bulk nano-MOSFETs. The resulting mean free path lambdao for backscattering in a long and near-equilibrium conductor is constant, regardless of the potential profile. However, the apparent mean free path lambda₁ in a local quasi-ballistic kBT layer depends on the curvature of the potential profile. In a linear potential profile, the lambda₁ extracted in a wide range of the conductor length (15 to 100 nm) and lattice temperature (150 to 300 K) is found to fall below lambdao. The carrier heating as the origin of reduced mean free path is inferred from the simulated carrier velocity distribution near the injection point. Strikingly, the mean free paths in a parabolic potential profile remain consistent: lambda₁ = lambdao. This indicates the absence or weakening of the carrier heating in the layer of interest, valid only for the parabolic potential barrier.