ZnO cluster assembled film with low defect concentration: towards ultra-low power sensors
Résumé
Small, low power sensors and actuators are vital for systems of all kinds to interact with their environment. Interest in gas sensing has been prompted from the need of monitoring our environment and particularly hazardous substances having negative effects on the environment and human welfare. Chemical sensors have been used extensively for the detection of hazardous pollutant gases, combustible gases and organic vapors. In this way, past few decades have found widespread applications for semiconducting metal nano oxides as solid-state gas sensors. The operating principle is based from the dependence of the conductivity through physisorption with the composition and the concentration of the surrounded atmosphere. Among them ZnO is very popular due to its superior reactivity, its non-toxicity, its chemical robustness, a large bandgap and a low synthesis price. However, the natural and often uncontrolled n doping, is a strong barrier for reproducibility results. We report a state of the art ZnO cluster assembled film nearly defect free which exhibit a huge and reproducible reactivity in a limited range of temperature. This perfect control of the defects is the key point for gas sensor upgrading with respect to the sensitivity, the selectivity, the reproducibility, the linearity and the life time. It takes an innovative look for reducing both size and power consumption allowing the integration in complex chips.