The Deal Fast-Surface States Are probably Deep-Level Impurities in the Semiconductor

A comparison is made between the widely held model that surface states (as described by Deal, et al.) are states that lie at the Si-Si02 interface (e.g., dangling bonds) and a model based on deep levels (heavy metals) in the semiconductor. It is shown that calculations based on the two models measure the same quantity but that a model based on dangling bonds is inconsistent with an observed dependence on oxide thickness. Deep-level impurities introduced during or after oxide growth, however, are expected to show a dependence on oxide thickness. Furthermore, the onset of the surface states is in agreement with that known for copper at 0.52 eV as measured from the valence band edge.