BAND-GAP SHIFT IN CDS - PHASE-TRANSITION FROM CUBIC TO HEXAGONAL ON THERMAL ANNEALING

The band-gap energies of CdS grown by chemical-bath deposition are obt ained by optical transmission and photoacoustic spectroscopy. These va lues and photoluminescence spectra are correlated over a range of ther mal annealing temperature, in which the evolution of sample structure is characterized by X-ray diffraction patterns. With increasing anneal ing temperature, the band gap reaches a minimum value. If is suggested that at this temperature a transition from a cubic to a hexagonal lat tice occurs.