Conductivity Studies in Europium Oxide

Abstract

The electrical and optical properties of EuO are studied in order to help determine conduction mechanisms. A strong relationship between growth parameters and electrical behavior is noted. Free-carrier absorption below the band edge in energy is observed in moderately conducting crystals. By comparing optical and electrical results, an experimental determination is made of carrier-density and scattering-time contributions to resistivity behavior. The carrier-density variations are explained in terms of an earlier proposed model which is developed here. The model consists of a donor-trap level, believed to be caused by an oxygen vacancy, which is above the conduction-band edge at low temperature, but crosses below it (near 50 \ifmmode^\circ\else\textdegree\fi{}K) with increasing temperature. Magnetoresistance and pressure results are presented which strongly support the model.