| Summary: | 碩士 === 國立成功大學 === 化學工程學系碩博士班 === 95 === Thin-film semiconductor is of use in an extremely wide of application, in recent years. The major sensing mechanism of semiconductor gas sensor is base on the change of electrical properties with gas composition, the gas sensitivity can be calculated as the ratio of the different resistances.In this paper, the Ti- and Pt- doped Ga2O3 thin films were prepared by rtheotaxial growth and thermal oxidation (RGTO). The morphology and crystallization of the thin films have been evaluated by SEM and XRD. In this study the sensing properties for ethanol were measured as functions of different dopants, doping process and dopant concentration.
The result shows that inner doping of Ti or Pt leads to an obvious change in morphology, and the nanostructures (nanoribbons and nanowires) affect the sensitivity of thin film and suitable dopant concentration can obtain the higher sensitivity. When the thin film doped with Pt on the surface, larger clusters are created during sensing and lead the resistance increasing and uncontinuous.
Dopant concentration influences sensitivity and lowers the optimum sensing temperature, which rises obviously when electrical properties convert p-type into n-type due to exceeding doping. The response time and recovery time decrease with increasing dopant concentration.
And we found that the response resistance rises due to the existence of water vapor during sensing, and it is irreversible. The variation of resistance depends on the water vapor concentration. So that the thin films prepared in this study are unstable to humidity.
|
|---|
