Production of SnO2 films by spray pyrolysis method and investigation of some physical properties

In this study, SnO2 films which belong to IV-VI group binary compounds have been produced by spray pyrolysis technique at substrate temperatures of 300 °C, 350 °C, 400 °C, 450 °C and 500 °C. To investigate the effect of substrate temperature on the physical properties of SnO2 semiconductor films, the structural, morphological and optical properties of the growth films have been investigated. Thicknesses of the SnO2 films have been measured by spectroscopic ellipsometry. X-ray diffraction studies showed that the samples have polycrystalline nature and the increasing of substrate temperature improves the structural properties of the films. Optical properties have been investigated and the highly transparent SnO2 films were found to have a direct band gap structure. It is obtained that the optical band gap decreases from 3.95 to 3.71 eV as the substrate temperature increases from 300 °C to 500 °C. Some optical parameters such as refractive index, extinction coefficient, dielectric constant and optical carrier concentration have been calculated from optical investigation. The surface topography of the films have been examined by field emission scanning electron microscope (FESEM). In these images, good adhesion onto substrate, a homogeneous distribution and existence of a granular structure on the surface have been noticed for the films obtained up to 350 °C. All of the results have been appreciated in point of view of optoelectronic device technology and it has been concluded that substrate temperature has a noticeable affect on each physical property.