Study On Preparation And Response Of Co-doped ZnO Film To CH₃COCH₃

Low concentration acetone sensors play an important role in monitoring of industrial production, food quality, stock raising and disease diagnosing. Therefore, it is necessary to detect the acetone gas. ZnO is one of the earliest semiconductor gas sensors which are used in daily life. Doping Co in ZnO, which changes materials surfactant, improves the sensitivity and selectivity of the film to acetone gas.Tin oxide thin film in this work is prepared on the surface of glass (ITO) by electrodeposition, doping with a small amount of Co, and then is oxidized at high temperature. The Co-doped ZnO sensing material is characterized by SEM and XRD. Analysis shows that the film surface is homogeneous and porous. The influences of voltage, temperature and fluid concentration on the thin film are studied. The optimized conditions of preparing Co-doped ZnO thin film are as follows:deposition voltage is-0.9V, deposition temperature is50℃, fluid concentration CZn2+=1.0mol/L, CCO2+=0.1mol/L.We assemble a sensing device and detect the sensing performances of Co-doped ZnO to acetone by the DC resistance method in the ammonia sintering temperature range of300-600℃. At400℃, the response sensitivity of Co-doped ZnO for100ppm CH3COCH3is8.57, and response and recovery time are shorter than others. In the range of200-400℃working temperature,350℃is the best working temperature. With the increase of gas concentration, the response of the this gas increases. And gas concentration and the response value show linear relationship. Furthermore, under the best conditions, the selectivity, reproducibility and stability of Co-doped ZnO sensors are better. The response mechanism of Co-doped ZnO for CH3COCH3gas is also discussed.