Highly sensitive SnO2 thin film NO2 gas sensor operating at low temperature

TLDR: In this article, the structural and morphological properties of thin nano-crystalline SnO 2 and WO 3 -doped SnO2 films are investigated using XRD, TEM and AFM.

Abstract: Thin films of pure nano-crystalline SnO 2 and WO 3 -doped SnO 2 in different concentrations (3 wt.% and 5 wt.%) are deposited using sol–gel spin coating technique on glass substrates. The structural and morphological properties of these films are investigated using XRD, TEM and AFM. The sensitivity and selectivity of these films are tested to different reducing and oxidizing gases such as SO 2 , NH 3 , NO 2 and ethanol. A SnO 2 thin film with 5 wt.% WO 3 shows very high responses to NO 2 (four orders of magnitude in the value of ( R g  −  R a )/ R a ; R g and R a are the resistance in NO 2 and in air, respectively) and excellent selectivity for NO 2 gas at a low operating temperature of 150 °C. The effect of WO 3 on the sensing characteristics of these films towards NO 2 is discussed.