Effect of thermal treatment on the CO and H2O sensing properties of MoO3 thin films

21st Latin American Symposium on Solid State Physics

Torres-Luengo, M.^1 ; Martínez, H.M.^1 ; Torres, J.^1 ; López-Carreño, L.D.^1

Grupo de Materiales Con Aplicaciones Tecnológicas, GMAT. Departamento de Física, Universidad Nacional de Colombia, Bogotá, Colombia^1

关键词: Chemical spray pyrolysis;    Crystallographic structure;    Electrical characterization;    Electrical resistances;    High-vacuum conditions;    I-V characteristic curve;    Increasing temperatures;    Substrate temperature;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/480/1/012009/pdf
DOI  :  10.1088/1742-6596/480/1/012009

来源: IOP

【 摘 要 】

MoO3thin films were prepared on Corning glass substrates using the chemical spray pyrolysis technique. A 0.1 M solution of ammonium molybdate tetrahydrate was used as precursor one. 5ml and 20 ml of the precursor solution was sprayed with the substrate temperature maintained at 623 K. Thermal treatment involved drying at 393 K for 8 h with continuous N2flow, followed by a vacuum annealing at 473 K for 2 h in a residual inert atmosphere. XRD indicates that the crystallographic structure corresponded to the orthorhombic α-MoO3phase. Electrical characterization was carried out in a system operating under high vacuum conditions. The samples could be cooled down to LN2temperature and heated in a controlled way up to 473 K. To elucidate the electrical response of the films to CO and H2O exposure, the I-V characteristic curve was measured over the whole temperature range. The electrical resistance of the films decreased with increasing temperature. In 5 ml films, the sensitivity to both gases increased which thermal treatment, reaching values between 40% and 60% at room temperature. On the contrary, the 20 ml films' sensitivity decreased almost half of their original values after thermal treatment.