Interface electronic structure of alkali halide contacts

The electronic structure of contacts of different ionic crystals was calculated for LiCl, NaCl and KCL using the LCAO method within the next-nearest-neighbour approximation. No localized states (interface states) were found which leads to the conclusion that the experimentally observed influence of such contacts on photoelectron spectra is mainly due to the changed position of the bottom of conduction band in the interface region. Calculated values are compared with measured shifts of photoelectron spectra and a reasonable qualitative agreement is obtained. We suggest that the contact of two ionic crystals can be treated as a classical Schottky barrier.