Summary:

As a major semiconductor, zinc oxide and tin dioxide such as doped and un-doped thin films have a wide range of application such as solar cells, electric, piezoelectric or luminescent devices and also as gas sensors and chemical sensors. Zinc oxide inevitably occupied a place among other metal oxides for many a applications, due to its unique combination of interesting properties such as non-toxicity, good electrical, optical and piezoelectric behavioral stability in a hydrogen plasma atmosphere and low price. As the material gas sensor, ZnO can be used to measure the reducing gases (CO and H2), O2, O3 and humidity. Recently, gas sensors based on nanocrystalline ZnO has attracted interest due to their good detection of toxic gases, alcohols and food freshness, especially fish freshness, or gas detection thin films integrated on one chip to make an "electronic nose". These thin films have been prepared by various spraying techniques, metalorganic chemical vapor deposition and pyrolysis. It is well known that the detection mechanism of semiconductor oxide gas sensor is based on the surface reaction and a high surface-volume ratio. Crystallite size and the porosity of the detection material nanowires are the most important factors for high sensitivity and short response sensors. Semiconductor gas sensors based on metal oxides have attracted the attention of ecologists and other researchers.

Hydrocarbon gases, including liquid petroleum gas (LPG) find useful applications as a clean source of energy for both the domestic and industrial areas. However, the explosive nature of liquid petroleum gas sensor makes requirement of reliable and effective gas sensors indispensable. Major constituent elements of liquid petroleum gas include butane ~ 70% -80%, propane ~5% -10%, propylene, butylene, ethylene and methane less than ~ 5%. Tin dioxide (SnO2) in thin layer form of a is most promising for gas sensing applications due to advantages such as high sensitivity, low cost, fast response and recovery rate. SnO2 exhibits sensitivity to various gases, and therefore catalysts are introduced to make the sensor selective. In addition to improving the selectivity, catalysts also modulate the electron transport properties of the sensing SnO2 layer and give improved response characteristics are obtained. In this project we present the results on the crystalline structure, morphology, optical and gas detections properties of nanofibrous and nanoporous ZnO and SnO2 thin films prepared by magnetron sputtering on optical fiber. Final purpose of this project is producing liquid petroleum gas sensor.