Electrical conductivity and Hall effect in n-type CdS

The experimental data of the temperature dependence of the electrical conductivity sigma(T) and the Hall coefficient R-H(T) on single crystal samples of n-type CdS reported in literature are reviewed and have been critically analysed including hopping conduction in an impurity band. It is shown that the experimental data of sigma(T) and R-H(T) reported in almost previous studies can be simultaneously fitted using a common set of the values of material parameters for calculating free-electron conduction, i.e. the conduction and the density-of-state effective mass of electrons, the acoustic-phonon deformation potential, the Frohlich coupling constant and the piezoelectric coupling coefficient, whereas wide ranges of values for these material parameters had been adopted in different studies. The correct assignment of impurity conduction mechanisms in n-type CdS single crystals is presented. In addition, reasonable explanations are given for unresolved enigmas regarding impurity pairing, unexpected large Hall mobility at low temperatures, and the effect of electric field on hopping Hall mobility.