Electron Concentration and Mobility in Semimetallic CdO

Abstract

Measurements of the Hall constant and mobility in the temperature range 81–1100 °K were carried out on n-type CdO single crystals with defect concentrations of 1.9–31.7 × 1018/cm3. Carrier concentrations were found to be independent of temperature, indicating complete ionization of the defect donors and semimetallic conduction. At high temperature the mobility appears to be limited by optical phonon scattering, while at low temperature ionized defect scattering is the dominant process. The apparent increase of the effective mass at low temperatures from 0.15 m0 to 0.45 m0 with increasing defect concentrations is ascribed to increasing nonparabolicity of the conduction band resulting from the addition of donor states to the band.