Low frequency dielectric properties of wide band-gap semiconductors

The complex dielectric constant has been measured for single crystal CdS and CdSe, and amorphous As2S3, As2Se3, and ZnSe at five audio frequencies 1000-10000 Hz over the temperature range 4.2-300 K at 1 atmosphere and over the pressure range 1-3000 atmospheres at temperatures from 260-320 K. Anomalies are noted in the temperature variation of the real part of the dielectric constant for the As glasses. One anomaly is attributable to a Debye-type impurity while the other remains unexplained. The volume independent temperature derivative and temperature independent volume derivative of the real part of the dielectric constant are calculated for each material. These are used in conjunction with the Clausius-Mossotti equation to evaluate the various contributions to the pressure and temperature derivatives of the dielectric constant. For CdS, the Lyddane-Sachs-Teller relation is found to hold and the Szigeti effective charge is calculated. Finally, the possible use of these materials as a pressure transducer is discussed.