Off-stoichiometry determination in CdTe crystals

In this work an easy method for determining the cadmium and tellurium excess in CdTe samples is presented. The technique showed an accuracy of better than 0.001 at.%, which is two orders of magnitude better than was previously reported. The technique is based on a detailed analysis of Cd and Te2 partial vapour pressures in equilibrium with CdTe samples at high temperatures. The partial pressures are determined by separately measuring the optical absorption of the vapours at the wavelengths of a He-Cd laser source (326 and 442 nm). The results of measurements of both Cd and Te-rich samples will be presented.