Reassignment of the OSe−VCd complex in CdSe

An IR absorption study of CdSe single crystals is presented. The as-received material revealed three absorption lines at 1094.2, 1107.5, and 1126.3 cm−1, which were previously assigned to the OSe−VCd complex [G. Chen et al., Phys. Rev. Lett. 101, 195502 (2008)] We show that each of the lines is accompanied by a number of weaker satellites with intensities which match the natural abundances of sulfur isotopes. In contrast to the original identification it is suggested that these peaks are local vibrational modes of a SOn complex. The three modes correspond to different orientations of the complex in the CdSe lattice. Arguments are presented in favor of 2 oxygen atoms (n = 2) in the complex. Measurements with uniaxial stress applied to the samples revealed defect symmetries and activation energies for the defect reorientation. The complex was found to be stable up to 750 °C