DONOR-ACCEPTOR PAIR LINES IN CADMIUM SULFIDE

We report the first observation of donor-acceptor pair lines in CdS. The spectrum correlates with a distant pair peak at 5176 , an I1 line at 4888.52 , and an I2 line at 4869.30 . Several other pair-line spectra were observed in the vapor-grown undoped platelets used in these experiments. One of these correlated with the same I1 line and distant pair peak, but with an I2 line at 4869.17 . Zeeman experiments confirmed that these lines were donor-acceptor pair lines. The Zeeman pattern of the pair lines could be predicted, using a crystal field and a j-j coupling constant. These constants were determined by the splittings of the pair lines in zero field. For Hc, the hole g value was the same as for an isolated acceptor. A theoretical wurtzite spectrum was calculated on the basis of Coulomb interactions. The spectrum was much more complicated than a theoretical zinc-blende spectrum and was sensitive to both the dielectric-constant ratio εεII and the ca ratio of the CdS lattice. The experimental lines could not be assigned, but the line densities were in agreement with what was expected for a pair-line spectrum involving a simple donor and acceptor. © 1969 The American Physical Society.