Use of Kubo formalism to study transport beyond the Born approximation: Application to low-temperature transport in Si metal–oxide–semiconductor field-effect transistors

A formalism is developed to study transport in semiconductor devices under conditions where the Born approximation and independent scattering approximations break down. The approach based on the Kubo formalism is applied to Si metal–oxide–semiconductor field-effect transistors (MOSFETs) where interface roughness effects cause the approximations mentioned above to break down at low temperatures. Results presented are the outcome of a numerical method based on a three-dimensional approach to examine the interface roughness effects on the electronic spectrum as well as on the transport in the MOSFETs. The dependence of mobility on temperature and gate bias are reported and the shortcomings of the Born approximations are outlined. The approach is general and can be applied to problems where scattering is very strong and localization effects are significant, e.g., in amorphous semiconductor devices. © 1998 American Institute of Physics