Determination of acceptor densities in p-type Hg1-xCdxTe by thermoelectric measurements.

The differential thermoelectric voltage of p-type bulk samples and epitaxial layers of Hgsub1minusxCdsubxTe (MCT) (0.2 smaller than x smaller than 0.25) in the temperature range from 20 to 300 K is measured using two different experimental techniques, the hot point method, and the lateral gradient method. The samples were also examined by Hall effect and conductivity measurements. In addition the Seebeck coefficient of p-MCT for acceptor densities 10high14 smaller than NsubA smaller than 10high17 cmhighminus3 is calculated employing empirical relations for the energy gap, the intrinsic carrier density, the carrier mobilities, and the LO phonon frequencies. By fitting the calculated temperature dependence of the thermoelectric voltage to the experimental one, the lateral gradient method proved to be an adequate tool for determining the effective acceptor density in p-type MCT including surface inversion. The hot point method is found to be insensitive to surface inversion. It may be use d for determining the temperature of zero thermoelectric power which directly yields a good estimate of the acceptor density.