PHOTOLUMINESCENCE OF CDTE THIN-FILMS CONTAINING A MIXED-CRYSTAL ORIENTATION

Photoluminescence spectroscopy was employed to study the effect of mixed crystal orientation on defect centers in CdTe thin films grown by metallo-organic chemical vapor deposition on a GaAs substrate. We show that some novel spectral features at 1.36 and 1.32 eV are observed when a substantial degree of both (211) and (331) CdTe are present and that these features disappear gradually if the sample is subjected to a series of low-temperature annealing steps under an inert atmosphere. Optimum annealing conditions, as indicated by the enhancement of the excitonic region, are established. Activation energies are estimated for the 1.59, 1.47, 1.36, and 1.32 eV bands and quantitative measurements are provided for the shift in transition energy due to temperature and annealing procedure. (C) 1995 American Institute of Physics.