Thermoluminescence of CdS single crystals annealed in various conditions

Thermally stimulated luminescence (TSL) glow curves were measured on CdS single crystals annealed in cadmium and sulphur vapour or air. The TSL glow curves were measured from liquid-nitrogen temperature to 500 K and nine glow peaks were observed at 110, 130, 190, 250, 280, 295, 320, 330 and 350 K with corresponding activation energies at 0.10, 0.18, 0.27, 0.32, 0.57, 0.82, 0.52, 0.78 and 0.83 eV. The activation energy and capture cross section for each of these peaks were calculated using a number of different analytical methods and compared with other data. The 190 K peak was the dominant feature observed in the crystal annealed in sulphur vapour so that the trap that lies 0.27 eV below the conduction band is associated with cadmium vacancies due to excess sulphur. For cadmium rich crystals, two characteristic traps appear at 280 and 350 K with depths of 0.57 and 0.83 eV. The 280 K peak was the dominant feature observed in the crystal annealed in cadmium vapour, associated with sulphur vacancies due to excess cadmium. (author)