Interface states at the SiO 2-Si interface

Abstract

The present understanding of interface states at the SiO 2-Si interface is reviewed. Typical results of measurement techniques are presented and critically discussed with respect to identification of types and origins of interface states. Only one type of interface state is observed after strong hydrogen annealing. The density of these interface states decays from D it ≧ 10 10 cm −2 eV −1 near the conduction band to extremely low values of D it ≦ 10 8 cm −2 eV −1 in the lower half of the Si band gap. A peak of interface states is observed below midgap. The density of bulk traps in silicon is comparable to the low interface state density. Among the various models of interface states proposed, the trivalent silicon dangling bond, bond angle distortions, and discrete traps in the interfacial layer are possible explanations of the various types of interface states.