多晶態三氧化鎢薄膜氣體感測器及添加催化劑銥之研究

Abstract

近年來，隨著科技的突飛猛進與環保意識抬頭，人們越來越重視環境與空氣污染的問題，使得氣體感測器的發展漸漸受到大眾的注意。為了改善傳統氣體感測器之昂貴、笨重與偵測耗時的缺點，近年來已有許多的研究專注於半導體材料薄膜氣體感測器的研發。本研究目的在研製短小輕薄的氣體感測器，來感測臭氣（H2S）和一般家用瓦斯，將此感測元件應用在日常生活中。

因為多晶態三氧化鎢(WO3)薄膜在氧化過程中為透明無色，且會在還原過程時變色，其具有寬廣的可見光譜吸收頻帶。在本實驗中，以磁控濺鍍法(R.F)濺鍍沉積三氧化鎢薄膜，再經由400℃、4小時的退火處理使薄膜轉變成多晶態，並添加微量的銥金屬微粒以改善此元件之感測靈敏度。並且我們分別探討此感測元件在不同薄膜厚度、不同工作溫度與添加催化劑後的感測靈敏度之變化特性，並討論其結果。

實驗結果顯示多晶態三氧化鎢薄膜會與臭氣、瓦斯產生作用而改變其電性，當工作溫度增加或感測氣體濃度改變時其電阻值也會相對的做出降低的反應。我們可以發現此微型感測器在對瓦斯的偵測上靈敏度較佳，當工作溫度在200℃，有添加催化劑銥的元件有較佳之靈敏度。

Recently, due to the wide-spreading consciousness of environmental protection and technological needs﹐more and more people begin to care for the problems of air and environmental pollution. Therefore, the study of gas sensor has been discussed gradually. However, there are some drawbacks of traditional gas sensors such as costs, heavy weight and time consuming and so many studies have been turned to focus on. semiconductor materials thin film gas sensor. Purpose of this research is to make a short､small､light and thin gas sensor to detect the H2S and general gas be used in our daily life.

In the process of oxidization, the Poly-WO3 film is transparent and colorless. Moreover, it also changes its color during reduction and presents broad seeable spectrum which is able to absorb the frequency band. In this study, the tungsten oxide（WO3）thin films is prepared by reactive RF magnetron sputter. The film is then stabilized by annealing in 400℃ of 4 hours and doped small amount of iridium to improve the sensitivity. The sensors were operated at the different thickness and working temperature to analyze the effect and added catalyst to test their differences and changes.

The result of experiment shows Polycrystalline WO3 Films is able to effect and change their electricity with H2S and gas. When working temperature increases or gas concentration changes, it makes the relative response. It is found the sensitivity of this sensor is better to detect gas. Also, when the working temperature is at 200℃ and the catalyst iridium is added, the sensor provides better sensitivity.