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 Hg1-x Cd(x) Te (MCT) (0.2 < x < 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 10(14) < N(A) < 10(17) cm-3 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 used for determining the temperature of zero thermoelectric power which directly yields a good estimates of the acceptor density.