Seebeck Effect in Cadmium Sulfide

Seebeck effect measurements have been made between 60°K and 300°K on the various n -type cadmium sulfide single crystals. In all the temperature range measured, the anomalous Seebeck voltages caused by “phonon-drag” are found. An apparatus for making measurements of the Seebeck effect and the method for calculating the ordinary electronic part of Seebeck coefficient for the case of CdS are described. The temperature dependence of the phonon-drag part of Seebeck coefficient ( Q p ) is ∼ T -2.5 for the sample of the least carrier number. It is observed that Q p has the anisotropy with respect to the crystallographic orientation. These data are compared with those in the case of ZnO in which piezoelectric scattering occurs as a result of electron-phonon interaction and phonons are scattered by the polarizable neutral donor states. Phonon relaxation times in CdS are also estimated from Q p .