Nucleation and growth of CBD-CdS thin films on ultrathin aluminium layers and annealing induced doping

Using chemical bath deposition CdS films were grown onto vacuum evaporated ultrathin aluminium films (25 nm). The Al/CdS bilayers thus formed were subjected to heat treatment at the temperatures 300 °C, 400 °C for 4 min and 500 °C for 90 s in a muffle furnace to facilitate aluminium to diffuse into the CdS films. XRD studies ascertained the shift of the lattice constant owing to introduction of Al into CdS crystal lattice by annealing CdS:Al at 400 °C. Secondary ion mass spectrometry indicated almost uniform distribution of aluminium atoms throughout the bulk of CdS subject to annealing. SEM images showed the distinct changes in surface morphology of CdS, grown on aluminium surface, from that on bare glass substrate. CdS:Al films (annealed at 400 °C) showed higher transmission in the visible range compared to pristine CdS.