Preparation of CdCr2S4 and HgCr2S4 thin films by chemical bath deposition

CdCr2S4 and HgCr2S4 thin films were deposited onto glass substrates by the simple chemical bath deposition method from aqueous alkaline and acidic baths, respectively. The films were uniform and adherent to glass substrates. They were characterized by structural, optical, and electrical measurement techniques. According to their X-ray diffraction patterns, CdCr2S4 films are polycrystalline with an estimated bandgap energy E-g of 2.6 eV, while HgCr2S4 films are amorphous with a bandgap energy equal to 2.7 eV. Scanning electron micrographs showed that the substrates were well covered with films; no cracks or pinholes were observed. Electrical resistivity of the as-deposited CdCr2S4 and HgCr2S4 films was found to be 1.44 X 10(5) and 2.39 X 10(5) Omega-cm at 350 K, respectively. According to thermoelectric power measurements CdCr2S4 and HgCr2S4 are of n-type nature. (C) 2000 Elsevier Science Ltd.