Study of interface roughness dependence of electron mobility in Si inversion layers using the Monte Carlo method

Abstract

The electron mobility in the inversion layer of a metal–oxide semiconductor field effect transistor formed on the (100) silicon surface is calculated by using a Monte Carlo approach which takes into account size quantization, acoustic phonon scattering, intervalley phonon scattering and surface roughness scattering. Degeneracy is also considered because it is important at higher normal effective fields (high gate voltages). The main emphasis is placed on the influence of the specific autocovariance function, used to describe the surface roughness, on the electron mobility. Here we compare the mobilities obtained using exponential and Gaussian autocovariance functions. It is found that the electron mobility calculated with roughness scattering rates based on the exponential function shows good agreement with experiments. The effect of the degeneracy and screening on the roughness scattering is also discussed.