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NiO thin films prepared by RF sputtering have been investigated for possible gas sensing application. The sensor films having thickness of around 30 nm were extremely smooth exhibiting a surface roughness of ~0.7 Å. These films exhibited a highly sensitive and selective response towards H2S at an operating temperature of 300°C. [ABSTRACT FROM AUTHOR]

We report synthesis of 100 nm thick cobalt oxide films - prepared by electron-beam evaporation of Co onto quartz (Q- films) and c-plane sapphire substrate (S- films) followed by oxygen annealing. Films have been characterized for their structure and morphology by using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The prepared films have been investigated for their chemiresistive gas sensing characteristics for a host of test gases (CH4, CO, NO2, Cl2, NH3 and H2S) as a function of operating temperature (between 50 and 350°C) and gas concentration (3-30 ppm). We demonstrate that both Q and S-films are highly selective to H2S at an operating temperature of 250°C. However it has been observed that films prepared on sapphire show much less base resistance drift as compared to the films on quartz substrate. [ABSTRACT FROM AUTHOR]

The gas sensing characteristics of ZnO nanowires (NWs) coated with different thickness of CuO film have been investigated. ZnO NWs were grown on Si/SiO2 by hydrothermal method and CuO films were deposited by thermal evaporation. It has been found that ZnO NWs exhibit characteristic n-type behavior upto a CuO thickness of 50 nm; whereas at higher thickness the samples show p-type behavior (typical of CuO). At a CuO thickness of 10 nm the sensitivity towards H2S was 500% more as compared to pure ZnO NWs films. In addition, the operating temperature was reduced to 200°C. [ABSTRACT FROM AUTHOR]

Hierarchical heterostructures consisting of W18O49 nanowires grown on CuO nanowires have been prepared and studied for their gas sensing properties. SEM images show that W18O49 initially grow as an shell over core CuO nanowire with protusion like branches whose thickness depends on oxygen partial pressure. These CuO:W18O49 structures were dielectrophoretically isolated and studied for their gas sensing properties. The results show potential of use of tailored hierarchical heterostructures for the fabrication of gas sensors. [ABSTRACT FROM AUTHOR]

RF sputtered SnO2 films were investigated for their response for various toxic gases (CO, NO, NH3, H2S, CO2, Cl2). These films were found to be highly sensitive and selective towards H2S. H2S gas sensing characteristics of these films have been studied as a function of temperature and concentration. These films were found to show maximum sensitivity (S = 54 for 10 ppm H2S) at a temperature of 150°C. Further, at this temperature, sensor response is found to vary linearly with concentration over a wide range from 500 ppb to 500 ppm. [ABSTRACT FROM AUTHOR]

Chemiresistive gas sensing properties of Fe2O3 thin films have been investigated. The sensor films were prepared by oxidation of Fe films, deposited by electron-beam evaporation method on sapphire substrates. We demonstrate that these films exhibit reversible response towards H2S in the concentration range of 1-50 ppm, with fast response and recovery times. Modification of these films by Au resulted in the enhancement of response towards H2S. Au, as a sensitizer helps in improving the sensors response by a spill-over effect. [ABSTRACT FROM AUTHOR]

Gas sensing properties of pure and Au incorporated WO3 thin films towards H2S and Cl2 have been investigated. The sensor films were able to detect H2S and Cl2 selectively at an operating temperature of 150 and 200 °C, respectively. Effect of gas concentration and Au loading have been investigated and correlated with the observed sensitivity values. Pure WO3 films exhibited better sensing characteristics towards H2S (S = 17, 10 ppm, 150 °C) while sensor film containing Au thickness of 21.6 nm exhibited a maximum sensitivity towards Cl2 (S = 89, 10 ppm, 200 °C).. [ABSTRACT FROM AUTHOR]