This paper reports about the implementation in a multisubband Monte Carlo device simulator of a comprehensive surface roughness scattering model, based on a nonlinear relation between the scattering matrix elements and the fluctuations Δ r) of the interface position. The model is first extended by including carrier screening effects and accounting for scattering at multiple interfaces, and it is then used for the analysis of relevant experimental data sets. We show that the new model can reproduce fairly well the silicon universal mobility curves as well as mobility data for ultrathin-body InGaAs MOSFETs using Δrms values consistent with atomic force microscopy (AFM) and TEM measurements. Our simulation results and some experimental data also indicate that mobility in InGaAs MOSFETs is reduced with decreasing well thickness, T W, with a weaker dependence compared with the TW 6 behavior observed in Si devices. © 1963-2012 IEEE.