Low temperature route to grow polycrystalline cadmium selenide and mercury selenide thin films

A simple, low temperature method has been developed to synthesize cubic CdSe and HgSe semiconductor thin films, based on chemical reaction of complexed CdSO4, Hg(NO3)2 with sodiumselenosulphate (Na2SeSO3) in aqueous alkaline medium at 278 K temperature. The films were characterized by using techniques of XRD, optical absorption, electrical measurements and AAS. The grown films were found to be uniform, well adherent, dark red, diffusely reflecting, polycrystalline in cubic form without trace of any hexagonallity. The CdSe film shows a double band gap at 2.15 and 1.86 eV, while the same for HgSe film occurs at 0.45 and 0.8 eV. Thermoelectric power measurements further indicated that the conduction takes place by n-type mechanism.