STRUCTURAL AND BANDGAP STUDIES OF ZNSXCDSE1-X THIN-FILMS

Thin films (t approximately 0.7 mum thick) of ZnSxCdSe1-x (0 less-than -or-equal-to x less-than-or-equal-to 1) were formed by thermal evapora tion on glass substrates kept at 300 K and 470 K. XRD studies showed t hat all the films were polycrystalline in nature. The wurtzite to zinc blende transition was found to take place in the composition region 0 .70 less-than-or-equal-to x less-than-or-equal-to 0.75. The lattice pa rameters of the films formed at a higher substrate temperature were gr eater than those deposited at a lower substrate temperature. Optical b andgaps also increased with substrate temperature. Bandgaps varied non linearly with composition, showing a downward bowing. The bowing param eter decreased with substrate temperature. The structural and bandgap studies clearly indicated a complete miscibility of the ZnS-CdSe syste m.