Synthesis and characterization of CdIn2O4 thin films by spray pyrolysis technique

Transparent conducting cadmium indium oxide (CIO) thin films were deposited onto preheated glass substrates by using spray pyrolysis technique with cadmium acetate and indium acetate as precursors for Cd and In ions, respectively. The films have been deposited at various substrate temperatures within 250-325 °C. As-deposited films were annealed at optimized temperature of 400 °C for 2 h in order to enhance the film properties under ambient air atmosphere. These films were characterized by X-ray diffraction (XRD), SEM, optical absorption and Hall effect techniques. The XRD studies reveal that films are of polycrystalline CdIn2O4 with cubic spinel structure and crystallinity increases appreciably after annealing. Optical absorption study shows the presence of direct optical transition and the band gap energy, estimated for as-deposited and annealed films were observed to be 3.1 and 3.0 eV, respectively. The decrease of electrical resistivity from 91.2 × 10−3 to 1.92 × 10−3 Ω cm have been observed after annealing, due to improvement in the crystallinity of the films. The highest figure of merit observed in the present study is 4.51 × 10−3 cm2 Ω−1.