Improved theory for remote-charge-scattering-limited mobility in metal–oxide–semiconductor transistors

Abstract

Transport theory is extended to include the remote-charge-scattering-limited electron mobility of metal–oxide–semiconductor field-effect transistors. We evaluated remote-charge-scattering from the depletion charge in the polycrystalline silicon gate. We obtained an analytical expression for the scattering potential, by taking image charge, screening, and quantization effects into account. The potential increases with decreasing gate-oxide thickness, which results in a mobility degradation at lower vertical electric fields. The calculated mobility agrees well with recent measurements.