Growth of Transparent Conductive Oxide SnO2 Thin Film as H2 Sensor

Abstract

 Tin dioxide (SnO₂) thin films are an advantageous group of metal oxides due to their high electrical conductivity. This transparent conductive oxide has an important place for electronic applications. The USP method, which is one of the thin film preparation techniques, is preferred in gas sensor systems due to its simple use and cheapness. The aim of this study is to examine the morphological and structural properties of tin oxide thin films using ultrasonic spray pyrolysis (USP) technique. The precursor SnCl₂ used in the process is 0.1M and 100 mL with deionized water. This solution prepared with deionized water and 0.1M /100mL SnCl₂ was sprayed onto the glass substrate for film coating. Significant peaks can be obtained in XRD plots due to evaporation when grown films are annealed at a temperature higher than the process temperature. The bandgap value of the sample before annealing is 2.95 eV, while the bandgap value after annealing is 2.5 eV. The sensor response graph of SnO₂ was obtained for 300°C and 10,000 ppm values. When samples produced at 350 °C were annealed to 450°C, improvement in morphological structure is detected, so the film quality and properties are highly dependent on temperature. The obtained XRD results support that the factor that homogenizes the crystallinity of the films is the increasing annealing temperature. It was observed that the sensor response increased after annealing. The increase in sensor response is due to the effect of additional heat treatment.