Layers of CdS were grown onto (111) CdTe substrates by means of chemical vapor deposition. The layers exhibited a high-quality hexagonal structure, and sharp luminescence lines which were attributed to the radiative recombination of excitons that were bound to donors and acceptors. In particular, 2 novel transitions (at 2.5458 and 2.5462eV) could be seen in the photoluminescence spectrum at 4K. In the case of bulk CdS, only one line occurred (2.5459eV) and was associated with the recombination of an exciton that was bound to a neutral acceptor. In order to identify the origin of the 2 new lines, the effects of temperature and of a magnetic field (parallel or perpendicular to the hexagonal axis) were investigated by using high-resolution photoluminescence spectroscopy. The results were quantitatively analyzed in terms of transitions from electronic states of the acceptor bound exciton complex (A0,X). It was shown that they could be understood if the 2 lines occurred at 2 different acceptor centers.

M.H.Nazare, C.Boemare, M.Assunção: Solid State Communications, 1994, 90[10], 655-8