Effect of substrate bias on the mobility and scattering time of electrons in si inversion layers

The dependence of the electron mobility and scattering time on the thickness of the inversion layer and its carrier concentration has been investigated. Electrons on (100) and (111) surfaces were studied. When only the lowest subband was occupied a linear dependence of the scattering time on the inversion layer thickness was observed. For fixed inversion layer thickness the scattering time decreased as the carrier concentration was increased. The carrier mobility appears to be limited by phonon and/or rigid core scattering processes. The effect of reverse substrate bias on the field effect mobility is similar to a change in the acceptor concentration of the substrate.