Carrier Surface Scattering in Silicon Inversion Layers

The field effect surface-channel conductance and transconductance of both p-type and n-type Si inversion layers were measured as a function of external field. In the small signal region, the channel conductance was found to vary logarithmically with the transverse field. The results are interpreted in terms of reduction of carrier mobility that is due to surface scattering. A model which consists of a uniformly distributed charge layer and self-consistent field is proposed to explain the observed results. It was found that in most samples measured a combination of specular and diffuse scattering is involved. Examples of completely diffuse scattering as well as the diffuse and specular combination are given. The temperature dependence of the surface mobility between 77° and 300°K is presented.