Experimental results of the study of the effect of irradiation with 230keV electrons and with X-ray photons with energies of 8.06 and 17.5keV and the effect of quenching on the formation and reconstruction of the centers of slow recombination of non-equilibrium charge carriers (the so-called r centers) in nominally undoped and Cu doped (NCu ∼1018/cm3) CdS single crystals were reported. It was shown that defects in cadmium sub-lattice in the crystal (specifically, the VCd vacancies and the CuCd defects with parameters close to those of the above vacancies) were responsible for the r centers. In the case of the X-ray irradiation of both undoped and Cu-doped CdS single crystals, sub-threshold defect formation of cadmium vacancies and CuCd defects takes place; this occurred at sites with distorted and weakened interatomic bonds, i.e., at “weak sites” near large structural imperfections of the lattice, of technological or other origin. Starting with a quenching temperature 170C, the spectrum of slow-recombination centers was appreciably affected by thermally formed vacancies VCd and secondary defects CuCd. At quenching temperatures higher than 250C, a significant contribution to the spectrum of optical quenching of photoconductivity was made by thermally introduced free (away from structural imperfections) r centers, i.e., the V Cd and CuCd defects.

Features of Subthreshold Defect Formation in CdS and CdS:Cu Single Crystals Subjected to Irradiation with X-Ray Photons. G.L.Mironchuk, H.Y.Davidyuk, V.V.Bozhko, V.Kažukauskas: Semiconductors, 2010, 44[5], 667-71