Charges and Dipoles at Semiconductor Interfaces

Abstract

AbstractThe formation of the Schottky barrier height at metal-semiconductor interfaces has often been discussed in terms of interface states. This paper examines theoretical models that specifically relate defects and other interface states (such as MIGS) to the interface dipole. These models usually rely on the assumption, which is also invoked in most experimental determination of interface state distribution, that the interface dipole can be broken up into the product of an interface charge and an interface distance/width. Various inconsistencies associated with this assumption are discussed, suggesting that the formation of the interface dipole is an integral process which cannot be divided. It is shown that the inclusion of the bond polarization at semiconductor interfaces, proposed in recent work, gives quantitative account of experimental Fermi level pinning effect. In addition, the bond polarization concept can be extended to the theoretical description of band offsets at epitaxial semiconductor heterojunctions. These results underscore the importance of correctly handling the chemistry at semiconductor interfaces in order to understand their electronic properties.