Effect of heat treatment on the characteristics and NH3 Sensing properties of Tin Dioxide SnO2 Thin Film

Abstract

In this research, Spray pyrolysis technique used to prepared Tin dioxide (SnO2) thin films on glass substrate with thickness about 200± 8 nm by dissolved 2.2563 g of SnCl2.2H2O in 100 ml of ethanol then added 60 drops from concentrated hydrochloric acid (HCl). After that the films were annealed at different temperatures (300, 400 and 400 °C ). X-ray analyses shows that the structure of all SnO2 films is polycrystalline with tetragonal rutile crystalline structure with preferential orientation in the direction (200).The optical measurements show that the optical transition has been direct and the average band gap has been tendency to decreases from 3.98 eV to 3.73 eV with increasing of Ta. The extent and nature of transmittance and optimized band gap of the material assure to utilize it for sensor applications.From sensing measurements for NH3 gas at different operating temperature (100,200,250 and 300)°C and gas concentration 1(5%, 10%, 15%, 20%, 25%, 30%, and 35% ) can be seen that the sensitivity increases with increasing operating temperature and gas concentration, the response time decreases to smallest value (4s) at operating temperature 200 °C while the recovery time (22 s).