Two-dimensional electron-lattice scattering in thermally oxidized silicon surface-inversion layers

Abstract

Theoretical calculations of the mobility in the thermally oxidized silicon surface-inversion layer for two-dimensional electron-lattice scattering at high surface electric field are presented for the low- and high-temperature cases. It is found that the effective deformation potential associated with lattice scattering of the inversion-layer electron is not necessaily constant for strongly inverted surfaces, i.e., the deformation potential will be surface-electric-field dependent when the electron channel density varies significantly over a lattice constant. In the high-temperature case, it is found that the calculated electron mobility is the same as that calculated by Kawaji if the deformation potential is assumed constant. In the low-temperature high-surface-electric-field case, the electron mobility is proportional to $E_S^{-\frac{5}{6}}$ (assuming the deformation potential to be constant) and $E_S^{-\frac{3}{2}}$ for a simple model of the lattice potential. The calculated results are extended to include different surface orientations and their effect on the occupancy of higher subbands due to the nonequivalence of the valleys. The comparisons of theoretical results with experimental measurements are made.