Studies on Selenide semiconducting thin films prepared from nanoparticles

Abstract

Thin films are fabricated by the deposition of materials on a substrate. A thin film is defined as a low-dimensional material created by condensing, one-by-one, atomic or molecular or ionic species of matter. Compared to bulk solids, thin films are having very large surface to volume ratio. The thesis deals with the hydrothermal synthesis, thin film deposition and characterization of selenides. Thin films were prepared by thermal evaporation and electron beam evaporation techniques. Deposited films were characterized with different techniques such as powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), UV-Vis-NIR spectroscopy and Hall effect measurement method to analyze the properties of the prepared films. ZnSe nano particles were synthesised at 205 °C using ZnCl2 and selenium metal powder. The tin selenide (SnSe) nano particles were synthesized using SnCl2.2H2O and selenium by hydrothermal process and the films were deposited by thermal evaporation technique. X-ray diffraction analysis shows that the films prepared at RT are amorphous in nature. The intensity of (104) peak increases with increasing substrate temperature. Optical band gap of the prepared films at various substrate temperatures lies in the range of 0.6-0.8 eV. 2D Atomic Force Microscope (AFM) image of film prepared at RT shows the surface with hillocks. SEM images reveal that the film prepared at RT has a smooth surface, 150°C contains spherical shaped particles. Well defined particles in the nanometer sizes were formed on the surface of the film prepared at 450°C. Thus increase in the substrate temperature effectively modifies the surface morphology of the films. The details of synthesis of source materials, deposition, characterization, summary of the present investigation and suggestions for future research work are presented. newline