Preparation of Semi-Insulating CdTe:In by Post-Grown Annealing After Elimination of Te Inclusions

Annealing under Cd-saturated overpressure within the temperature range of 700-800degC was used for elimination of Te inclusions in high resistive In-doped CdTe. Te inclusions were significantly reduced by annealing and only residual inclusions with dimensions less than 1 mum remained in the material. All annealed samples were converted to the high conductive n-type after Cd-saturated annealing. Annealing finished by quenching at 550degC, 650degC, and 750degC under various Cd/Te overpressures was used to find an annealing conditions leading to the preparation of a semi-insulating material. The range of optimal overpressures was found to be very narrow and keeping these conditions during annealing and quenching is practically impossible. The semi-insulating material was prepared by means of Te-rich annealing finished by slow cooling. The annealing temperature, In doping concentration, and cooling regime were observed to strongly affect the preparation of semi-insulating material.