Chemical bath deposition of CdS films on different substrate orientations

Cadmium sulfide (CdS) thin films were prepared by the chemical bath deposition (CBD) technique on glass substrates under different substrate orientation and two agitation modes of the bath. Groups of CdS films were grown onto horizontal, vertical, and 45° inclined substrates, meanwhile the chemical bath was affected by magnetic or oscillating agitation. Optical homogeneity was studied by means of the band gap energy measured on different sites of the film. Morphology, thickness, stoichiometry and crystalline structure of films were characterized by atomic force microscopy, profilemetry, energy dispersive spectroscopy, and X-ray diffraction techniques, respectively. Relations between measured properties, substrate orientation and agitation types are discussed. In all cases, a cubic phase with (111) as main peak diffraction was obtained in films. Oscillating agitation in bath produces large grain size with low roughness, constant deposition rate and better crystal orientation as compared with magnetic agitation. CdS films grown on vertical substrates result with low roughness, high Cd/S ratio, band gap energy values near to the typical value (2.42 eV) and better crystalline structure than other substrate orientation.