Effect of deposition time and complexing agents on hierarchical nanoflake-structured CdS thin films

Hierarchical nanoflake-structured CdS thin films have been prepared using chemical bath deposition method at two deposition intervals with different complexing agents. As complexing agents, ammonia and ammonia with triethanolamine or ethylene-diamine-tetra-acetic acid were taken. Structural, optical and morphological studies of the as-deposited CdS films have been studied using X-ray diffraction, UV-Vis and Raman spectroscopy, atomic force and field emission scanning electron microscopy. Compositional analysis reveals that near stoichiometric thin films of CdS were deposited at higher deposition time. X-ray diffraction patterns confirmed the cubic phase of the deposited films and the calculated crystallite sizes increased with higher deposition time while both dislocation densities and micro-strains were found to decrease with increase in deposition time. Field emission scanning electron microscopy shows the formation of hierarchical nanoflakes having small voids at lower deposition time, however, the density of the nanoflakes increases with increase in deposition duration. UV-Vis-NIR spectroscopy was performed in the spectral range 350-1100 nm which confirmed that the synthesized films contain good optical transparency in the range of 85-95% and the calculated bandgaps were found in the range of 2.20-2.42 eV. Raman spectroscopy indicated a strong electron-phonon coupling for films deposited for longer duration as the particle size increased.