Effect of deposition temperature on structural, optical and electrical properties of chemically deposited thermochromic Cu2HgI4 thin films

Copper mercury tetraiodide thin films were grown by the chemical bath deposition technique at different deposition temperatures varying from 300 K to 345 K. The structural properties of the prepared Cu2HgI4 thin films show that the Cu2HgI4 films have a polycrystalline nature. The compositional analysis confirmed the nearly stoichiometric structure of the deposited Cu2HgI4 thin films. Homogeneous and regular surface morphology, including of circular-shaped grains with a size range from 31 to 46 nm, was revealed. Thermal stability and phase transition were studied by means of thermogravimetric analysis (TGA) and differential thermal analysis (DSC), respectively. The effects of deposition temperature on the optical properties and D.C. electrical conductivity of the Cu2HgI4 films have been studied. The films were found to have an indirect optical energy gap of values increases with increasing substrate temperature. The electrical conductivity increases with increasing temperature according to grain boundary trapping model.