GROWTH AND CHARACTERIZATION OF SnSe THIN FILMS PREPARED BY SPRAY PYROLYSIS TECHNIQUE

Abstract

Tin selenide (SnSe) thin films have been deposited using chemical spray pyrolysis on nonconducting glass substrates at temperatures from 250 oC, 300 oC, 350 oC, and 400 oC. The composition, surface morphology, structural, optical and electrical properties of deposited films were studied using energy dispersive analysis by X-rays (EDAX), scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectrometry and four probe techniques. EDAX analysis yielded an atomic ratio of (50.3) Se: (49.7) Sn. SEM studies reveal that the SnSe films exhibited uniformly distributed grains over the entire surface of the substrate. The XRD studies reveal that all the films are crystalline with orthorhombic structure. Microstructural parameters such as crystallite size, micro strain, and dislocation density are calculated and found to depend upon temperatures. The optical band gap of SnSe thin films is evaluated using transmittance and absorbance data. A direct band gap of the 1.08 eV is estimated and the value is in conformity with 1.1 eV reported earlier for SnSe thin films. The electrical resistivity shows that the films are semiconducting and the resistivity is found to be minimum at optimized substrate temperature.