Study On Gas Sensing Properties Of SnO₂ Thin Films Deposited By DC Reactive Magnetron Sputtering

The present status of selectivity research and new development of semiconductor gas sensor is introduced,and the doping technology of metal oxide semiconductor gas sensors is commented. The doping of the semiconductor gas sensors and its influence on sensitivity and selectivity of the gas sensors is presented.Nanosized SnO₂ thin films doped with ZnO and CuO were respectively prepared on Si(111) and Al2O3 substrates by DC Reactive magnetron sputtering. Annealing was carried out for SnO₂-ZnO thin films at 500oC and 800oC, and for SnO₂-CuO thin films at 500oC and 700oC ,respectively.Three samples of nanosized SnO₂ thin films doped with ZnO showed different sensitivity towards the ethanol when the operating voltage was lower (4.5- 6V ). As the operating voltage rised, the sensitivity to the ethanol was reduced for the sample without annealing; Meanwhile, when the operating temperature was lower (4.5- 6V), each sample showed sensitivity to the acetone too, but when the operating temperature was higher (above 6V), the sensitivity to the acetone for the sample after 500 oC annealing increased sharply, being nearly close to 100.It hopes that the operating temperature is as lower as possible,optimum sensitivity effect can be obtained for the sample at 800 oC annealing.Nanosized SnO₂ thin films doped with CuO were respectively prepared on Si(111) and Al2O3 substrates by DC Reactive magnetron sputtering. Annealing was carried out,respectively,at 500oC and 700oC. Each sample was tested by Gas-sensitivity measurement instrument, the sample after 500oC annealing showed basically higher sensitivity towards the different tested gas.The high was the operating temperature,the worse was the sensitivity. The sample showed good selectivity and sensitivity towards ethanol vapor after 700 oC annealing, when the operating voltage was 6.5V, it showed good gas sensitivity even for the lower density of ethanol vapor.