ZnO thin film sensors for detecting dimethyl- and trimethyl-amine vapors

Undoped and Al-doped ZnO thin films were deposited on quartz substrates using an indigenously developed modified chemical vapor deposition technique. Microstructures of the deposited films were optimized by adjusting various growth parameters. The baseline resistance of the ZnO film sensors was stabilized by annealing the as-deposited films periodically in an oxidizing and reducing ambient at maximum operating temperature. The sensor parameters were studied by exposing the optimized ZnO thin films to low concentrations of dimethylamine (DMA) and trimethylamine (TMA), the chemical species released from harvested fish and other seafood with ageing. The effect of operating temperature was found to play a vital role in determining the sensitivity and resolution of the sensor. While the undoped ZnO film surface, sensitized with palladium, exhibited higher DMA sensitivity than that of TMA, an enhanced TMA sensitivity was noticed with the ZnO films doped with aluminum.