The influence of interfacial roughness on parallel transport at oxide–semiconductor and heterojunction interfaces

Abstract

Carrier scattering due to surface roughness at a nonideal interface may be an important mechanism in reducing carrier mobility and ultimately semiconductor device performance. We have investigated the role of this scattering mechanism in the low and high field transport of carriers parallel to oxide–semiconductor and heterojunction interfaces through analytic solutions and Monte Carlo simulation of the carrier dynamics. Quantitative differences between the scattering rates in the two types of systems arise from image potential contributions due to the presence of the dielectric in the oxide–semiconductor system which increases the scattering rate relative to a homogeneous system. For the InP/SiO2 system, surface scattering limits the surface channel mobility, even at room temperature. However, from detailed Monte Carlo simulation of high field transport in n-type InP inversion layers, we find that roughness scattering plays a relatively small role in reducing the peak and saturated carrier velocities since interface scattering is elastic and decreases with electron temperature. Thus, the short channel behavior in InP metal–oxide semiconductor field effect transistors may be comparatively better than that indicated by long channel results.