WO3 thin films prepared by pulsed laser deposition

We report the structural and gas sensing properties of tungsten trioxide (WO3) thin films prepared by the KrF excimer pulsed laser deposition technique. The WO3 thin films having amorphous, crystallized tetragonal and triclinic structures were fabricated at the oxygen pressure of 10-300 mTorr and the substrate temperature of 150-800degreesC. We revealed the effect of the oxygen pressure and substrate temperature during the deposition on the crystal phases of the WO3 thin films. The atomic force microscopy measurement shows that the average grain size and the average number of grains are approximately 200 nm and 8/mum(2), respectively. The triclinic WO3 thin film with a thickness of 1 mum showed high sensitivity of 254 in NO (60 ppm) gas at a low operating temperature of 150degreesC.