ZnO/Ti Thin Film: Synthesis, Characterization and Methane Gas Sensing Property

Thin films of ZnO were synthesised on glass substrate by dc sputtering technique at a system pressure of 10⁻⁴ Torr. A layer of TiO₂ was deposited onto the above ZnO films by high pressure sputtering technique. The composite structure was then subjected to rapid thermal annealing at a pressure of 10⁻² Torr in argon ambience. Microstructural and compositional analyses were carried out by SEM, EADX and XRD studies. The optical band gap pure ZnO (∼3.45 eV) was found to shift to higher energy (∼3.54 eV) for the ZnO/Ti structures. FTIR measurement indicated the presence of a prominent absorption peak at ∼490 cm⁻¹ due to ZnO stretching mode. Methane gas sensing measurement was carried out at 353K, indicated that the highest sensitivity was nearly 60% with a response time ∼52 min when the film were exposed to 10 % vol. of methane gas.