利用陽極氧化鋁模板製備奈米級二氧化鈦有害氣體感測元件之研究

Abstract

本研究旨在製備出奈米級二氧化鈦氣體感測元件來感測有害氣體，在陽極氧化鋁(Anodic Aluminum Oxide, AAO)模板濺鍍白金(platinum, Pt)作為導電極，再以蒸鍍鋁(Aluminum, Al)作為薄膜支撐的底座，經由濕式蝕刻的方法去除AAO的阻障層以及擴孔處理，最終以原子層沉積法將二氧化鈦(Titanium Dioxide, TiO2)沉積於製備好的模板中形成奈米結構。製作的過程中探討不同製程參數所形成的二氧化鈦奈米結構的表面形貌與晶體結構，其性質以掃瞄式電子顯微鏡(Scanning Electron Microscopy, SEM)、能量色散X射線光譜(Energy-dispersive X-ray Spectroscopy, EDS)檢測。製作完成之奈米級有害氣體感測元件，以氣體感測設備來量測甲醛(Formaldehyde, CH2O)、一氧化碳(Carbon monoxide, CO)氣體之反應靈敏度，實驗結果顯示奈米級二氧化鈦有害氣體感測元件，以溫度和氣體濃度的實驗參數搭配。在室溫(25˚C)下感測CH2O靈敏度最高為37.1%；感測CO靈敏度最高為24.0%。然而在加熱的狀態下，感測CH2O在0.5 ppm、500˚C時其靈敏度最高為63.2%；感測CO在600 ppm、500˚C時其靈敏度最高為90.2%。In this study, a metal oxide semiconductor gas sensor was fabricated to detect harmful gases. A metal oxide semiconductor was a nano titanium dioxide (TiO2) produced by atomic layer deposition (ALD) in anodic aluminum oxide (AAO) template. An anodic aluminum oxide was suitable for producing nanotube or nanowire process. It had high porosity, good regularity and good array. In producing process of sensor, sputter platinum (Pt) on the AAO as layer of conductive, then thermal vapor aluminum (Al) as the base to support the film. The barrier layer of AAO is removed by wet etching and the hole expansion is processed. Finally, TiO2 was deposited on the prepared template by atomic layer deposition to form a nano structure. Using this sensor to detect formaldehyde (CH2O) and carbon monoxide (CO) at the different concentration and temperature. The experimental results show that the highest sensitivity for detecting CH2O and CO at the room temperature (25˚C) were respectively 37.1% and 24.0%. The highest sensitivity for detecting CH2O and CO at the heat situation were respectively 63.2%, 0.5 ppm at 500˚C and 90.2%, 600 ppm at 500˚C.