Activation Energy Analysis of Defect Levels in Semi-Insulating CDTE Detector Material

The electrical properties of semi-insulating n-type cadmium telluride single crystals grown using the solvent evaporation technique are reported. Measurements of thermal activation energies for both Ohmic and space charge limited conduction over a broad temperature range have been used to determine the locations and densities of the localised levels in this material. The two dominant levels are situated at approximately 0.31 eV and 0.56 eV from the conduction band. The position of the deeper level correlates well with the reports of other investigators of detector grade CdTe. However, our analysis suggests that previous interpretations of experiments on CdTe showing linear portions in curves of log J versus reciprocal temperature, might well be re-examined.