Relative importance of phonon scattering to carrier mobility in Si surface layer at room temperature

Abstract

The room‐temperature surfacemobility of free carriers in metal‐oxide‐semiconductor systems has not been satisfactorily explained by treating phonons as the only important scattering mechanism. The present work shows that, in addition to phononscattering, both Coulombic and surface‐roughness scattering must be taken into account. Experimental results are presented showing that, contrary to the prediction of phononscattering,surfacemobility is process dependent, and that a strong correlation is observed between the detailed mobility behavior and the surface‐state density and the degree of surface roughness. A theoretical calculation of surfacemobility, based on the combined effect of scattering due to phonons, charged centers, and surface roughness, is also presented.