Gas-sensing properties and sensitivity promoting mechanism of Cu-added SnO2 thin films deposited by ultrasonic spray pyrolysis ☆

Abstract Tin oxide-based thin films for gas sensors were deposited by the ultrasonic spray pyrolysis technology. The thin films were porous and comprised nano-sized crystallites with fast responses to the H2S gas. The sensor performance was observed to be enhanced by the Cu additive, which was incorporated at the Cu/Sn ratio of 0–1. The influences of Cu-doping amount on the gas-sensing properties were discussed. The values of power law exponent n for each thin film sensor were calculated to discuss the sensitivity of the sensors, which was promoted by the Cu additive. Two mechanisms were found to be responsible for determining the sensitivity of Cu-doped SnO2 thin films. One is the known receptor function of the SnO2 grain, and the other is the promoting mechanism caused by the transformation between CuO and CuS in the H2S detection. The former one produces a temperature-dependent sensitivity, which is ascribed to the various types of adsorbed oxygen on grain surface at different operating temperatures. The latter one results in a promoted sensitivity according to the present evaluation. The contribution of each mechanism to the thin film sensors with various Cu/Sn ratios was discussed.

[1]  Peng Sun,et al.  Microwave assisted synthesis of hierarchical Pd/SnO2 nanostructures for CO gas sensor , 2016 .

[2]  Zhaoxia Zhai,et al.  Numeral description of grain size effects of tin oxide gas-sensitive elements and evaluation of depletion layer width , 2015, Electronic Materials Letters.

[3]  Zhaoxia Zhai,et al.  Simulation of the grain size effect in gas-sensitive SnO2 thin films using the oxygen vacancy gradient distribution model , 2015, Electronic Materials Letters.

[4]  Makoto Egashira,et al.  Temperature programmed desorption study of water adsorbed on metal oxides. 2. Tin oxide surfaces , 1981 .

[5]  Yasutaka Ozaki,et al.  Effects of surface modification with platinum and ruthenium on temperature and humidity dependence of SnO2-based CO gas sensors , 2000 .

[6]  Kengo Shimanoe,et al.  Receptor function of small semiconductor crystals with clean and electron-traps dispersed surfaces , 2009 .

[7]  E. Jette,et al.  Precision Determination of Lattice Constants , 1935 .

[8]  Zhaoxia Zhai,et al.  Characterization and Gas Sensing Properties of Copper-doped Tin Oxide Thin Films Deposited by Ultrasonic Spray Pyrolysis , 2016 .

[9]  Koji Ito,et al.  H2S sensing property of porous SnO2 sputtered films coated with various doping films , 2006 .

[10]  S. Morrison.  Selectivity in semiconductor gas sensors , 1987 .

[11]  R. K. Bedi,et al.  Surfactant assisted growth of nanostructured tin oxide films for gas sensing applications , 2011 .

[12]  Norio Miura,et al.  Dilute hydrogen sulfide sensing properties of CuO–SnO2 thin film prepared by low-pressure evaporation method , 1998 .

[13]  T. Seiyama,et al.  A New Detector for Gaseous Components Using Semiconductive Thin Films. , 1962 .

[14]  Tae-Sung Oh,et al.  CO sensitivity of La2O3-doped SnO2 thick film gas sensor , 2013 .

[15]  Dongxiang Zhou,et al.  Tin oxide thin films prepared by aerosol-assisted chemical vapor deposition and the characteristics on gas detection , 2010 .

[16]  Udo Weimar,et al.  Influences of Al, Pd and Pt additives on the conduction mechanism as well as the surface and bulk properties of SnO2 based polycrystalline thick film gas sensors , 2012 .

[17]  Subho Mozumdar,et al.  Influence of CuO catalyst in the nanoscale range on SnO2 surface for H2S gas sensing applications , 2005 .

[18]  Kengo Shimanoe,et al.  Two types of moisture effects on the receptor function of neat tin oxide gas sensor to oxygen , 2013 .

[19]  Norio Miura,et al.  CuO-SnO2 element for highly sensitive and selective detection of H2S , 1992 .

[20]  Noboru Yamazoe,et al.  Interactions of tin oxide surface with O2, H2O AND H2 , 1979 .

[21]  Kengo Shimanoe,et al.  Extension of receptor function theory to include two types of adsorbed oxygen for oxide semiconductor gas sensors , 2012 .

[22]  L. A. Patil,et al.  Heterocontact type CuO-modified SnO2 sensor for the detection of a ppm level H2S gas at room temperature , 2006 .

[23]  A. L. Patterson.  The Scherrer Formula for X-Ray Particle Size Determination , 1939 .

[24]  Xianglan Xu,et al.  O2 adsorption on MO2 (M=Ru, Ir, Sn) films supported on rutile TiO2(110) by DFT calculations: Probing the nature of metal oxide-support interaction. , 2016, Journal of colloid and interface science.

[25]  Dongxiang Zhou,et al.  Properties and mechanism study of SnO2 nanocrystals for H2S thick-film sensors , 2009 .

[26]  Xiaojing Zhao,et al.  Templated bicontinuous Tin oxide thin film fabrication and the NO2 gas sensing , 2016 .

[27]  Zhou Dongxiang,et al.  Highly sensitive SnO2 thin film with low operating temperature prepared by sol–gel technique , 2008 .

[28]  Lin Quan,et al.  Evaluation of depletion layer width and gas-sensing properties of antimony-doped tin oxide thin film sensors , 2015 .