ABSTRACT
Samarium monosulfide has a number of unique properties associated with its energy band structure. The band gap of SmS includes localized levels formed by the 4f shells of the samarium ions and located close to the conduction band. The energy gap between these 4f levels and the lower edge of the conduction band depends strongly on the distance between the ions forming a crystal. Displacements of atoms due to introduction of defects alter the distance between the nearest neighbors and in the case of SmS this may change greatly the energy band structure.
