Ab initiovalence band offsets between Si(100) andSiO2from microscopic models

Abstract

We theoretically investigate the valence band offsets (VBO's) between silicon and crystalline oxides. Using the local density functional approximation, we calculate valence band offsets using standard interface methods, idealized surface ionization potentials and partial density of states. Between silicon (100) and strained model oxides the VBO is $3.1\ifmmode\pm\else\textpm\fi{}0.3\mathrm{eV}.$ These results are $\ensuremath{\approx}1.0\mathrm{eV}$ lower than experimentally derived values for silicon-amorphous oxide junctions. In contrast, valence band offsets between silicon (100) and $\ensuremath{\alpha}$ quartz are close to the experimental values. The implications of these results are discussed.