Photoluminescence study of deep levels in Cr-doped ZnSe

Single crystals of intrinsic ZnSe were grown by the seeded physical vapor t ransport method and the diffusion doping was utilized to incorporate Cr in these crystals. The radiative recombinations in these samples with Cr conce ntration in the range 1.0 - 10.2 x 10(19) cm(-3) were studied by the steady state photoluminescence technique. It was found that the Cr deep centers i nhibit the band-to-band emission in Cr-doped ZnSe. Except in undoped single crystals, no emission corresponding to the band-to-band transition was obs erved from any of the doped samples. Instead, the higher wavelength emissio ns associated with Cr deep levels were obtained. This capture of photoexcit ed carriers by deep centers was verified using different excitation wavelen gths. The role of chromium impurities in nonradiative recombination process es was also evidenced from the sharp decreases in the deep level emission i ntensity with increasing Cr concentration. (C) 1999 American Institute of P hysics. [S0021-8979(99)07701- 4].