Electrical Conduction inn-Type Cadmium Sulfide at Low Temperatures

Measurements of the Hall mobility and electrical conductivity of $n$-type CdS were made between 1.8 and 294°K. Both Ohmic and non-Ohmic regions were studied at low temperatures. In these undoped crystals, a donor level of 0.021 eV, believed due to excess Cd, was found. Below 22°K, charge transport by impurity conduction was observed. The electric field dependence of the conduction-band mobility was found to be caused by hot-electron effects and the acoustoelectric effect. Good agreement between hot-electron theory and experiment was obtained when ionized-impurity as well as acoustic-phonon scattering were included in the theory. To obtain satisfactory agreement between theory and experiment, electron-phonon interactions via deformation and piezoelectric potentials were included. In the impurity-conduction region, variations of the Hall mobility with electric field were shown to be caused by the hot-electron behavior of the conduction-band electrons.