Effect of Substrate Surface on the Wide Bandgap SnO2 Thin Films Grown by Spin Coating (2209.09460v2)

Abstract: Tin (IV) oxide (SnO2) sols have been synthesized from SnCl2.2H2O precursor solution by applying two different processing conditions. The prepared sols were then deposited on UV-Ozone treated quartz and soda lime glass (SLG) substrates by spin coating. The as-synthesized film was soft-baked at about 100 deg. C. for 10 min. This process was repeated five times to get a compact film, followed by air-annealing at 250 deg. C. for 2 hours. The pristine and annealed films were characterized by UV-Vis-NIR spectroscopy, Grazing Incident X-Ray Diffraction (GIXRD), and Field Emission Scanning Electron Microscope (FESEM). The effect of the substrate surface was investigated by measuring the contact angles with De-Ionized (DI) water. UV-Ozone treatment of substrate provides a cleaner surface to grow a homogeneous film. The electrical resistivity of annealed thin films was carried out by a four-point-collinear probe employing the current reversal technique and found in the range of approx. 2x10^3 to 3x10^3 Ohm-cm. Film thickness was found in the range of approx. 137-285 nm, measured by a stylus profilometer. UV-VIs-NIR Transmission data revealed that all the thin film samples showed maximum (82-89) % transmission in the visible range. The optical bandgap of the thin films was estimated to be approx. 3.75-4.00 eV and approx. 3.78-4.35 eV for the films grown on SLG and quartz substrates, respectively.