Synthesis And Optical Characterization Of Mercury Diselenide (HgSe2) Thin Films

The stoichiometric mercury diselenide (HgSe2) thin films were prepared by using an electrodepositions technique. The mercury diselenide (HgSe2) thin films were deposited on both the ITO- glass substrates for optical characterization and the stainless steel substrates for the structural and surface morphological characterization. The cyclic voltammetry analysis was done in order to select the best deposition potential which then followed by deposition of thin films process. The selected deposition potential are -1.2, -1.4, -1.5 and -1.6 V. The bath temperature was maintained at 40 ± 2°C. The time taken for each deposition was set at 30 minutes. The thickness of the thin films was measured using weight gain method. The thickness of the thin films was in the range of 1.2651 μm to 2.1084 μm deposited on stainless steel substrates. Based on the X-ray Diffraction analysis, the intense peaks were at deposition potential of -1.6 V. The thin film is confirmed to be polycrystalline in nature and possessed cubic structure with lattice parameters values a = b = c = 6.08 A. From Scanning Electron Microscope (SEM) analysis, it was proven that when the potential deposition is increase; the surface of the thin film will become non-uniform. The highest deposition potential which is -1.6 V been applied shows a crack on the film’s surface. However, the data from UV-Vis-NIR Spectrophotometric measurement revealed that the optical band gap values of the HgSe2 thin film decreased with the increasing of potential voltage which is between 2.91 eV for -1.2 V and 2.37 eV for -1.6 V. The positive slope of the graph plotted from UV-Vis-NIR Spectrophotometric measurement shows that the band gap of HgSe2 thin film is direct.