Growth and characterization of nanocrystalline CdSe thin solid films

Abstract

In this paper we report the best conditions for growth of thin films of cadmium selenide (CdSe). The chemical bath deposition technique was used to deposit thin solid films of CdSe on to glass substrates. In this technique, cadmium acetate and sodium seleno sulfate were used as Cd2+ and Se2− ion precursors, respectively. 2-Mercaptoethanol was used as a capping agent. X-ray diffraction, atomic-force microscopy, scanning electron microscopy, and energy-dispersive X-ray analysis were used to determine the structure, morphology, and elemental constitution of these films. Photoluminescence studies revealed the effect of capping agent on the size of the CdSe nanoparticles. The optical properties were investigated by use of UV–visible absorbance spectroscopy. On annealing at 573 K, the phase of as-deposited CdSe thin films was transformed from metastable cubic (zinc blende) to hexagonal (wurtzite). The band gap energy for bulk, capped, and annealed films was estimated, and found to be 1.7, 2.3, and 2.04 eV, respectively.