Evidence of a stoichiometry-related compensation in undoped high-resistivity CdTe crystals

Nominally undoped CdTe crystals are grown by both vapour phase and Bridgman technique. The stoichiometry of the feed charge was adjusted in order to obtain n-type, p-type and high resistivity crystals. The stoichiometry of CdTe samples is studied by means of a detailed analysis of the temperature dependence of the equilibrium partial pressures of Cd and Te2 vapours. A strong evidence of a correlation of the stoichiometry and the resistivity of the samples has been found. This suggests that a stoichiometry related defect plays an important role in the compensation mechanism of the nominally undoped crystals. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)