Origin and role of elasticity in the enhanced DMMP detection by ZnO/SAW sensor

ZnO/Quartz based surface acoustic wave (SAW) sensors have been fabricated for the detection of DMMP (di-methyl methyl phosphonate) at room temperature. The as-deposited ZnO thin films are c-axis oriented. The sensitivity of the sensor toward DMMP vapors increases with increase in the thickness of ZnO thin films. A change in elasticity of ZnO films with exposure to DMMP vapors is the dominant sensing mechanism. Various properties of ZnO thin films (roughness, porosity, crystallite size, bond strength etc.) responsible for elastic changes are analyzed by depositing the films under different processing conditions. The ZnO/SAW sensor is also highly selective toward DMMP vapors as compared to other interferants. The results throw light into the elasticity mechanism for SAW sensing along with the possibility of utilizing ZnO/SAW sensor for DMMP detection.