利用陽極氧化方式在石英基材上製備二氧化鈦奈米柱陣列

Abstract

陽極氧化鋁模板至今已研究達數十年之久，而近年來已有研究指出利用陽極氧化兩種不同離子阻抗的雙金屬層方法來製作金屬氧化物的奈米點、奈米管或是奈米柱陣列。本研究主要為利用陽極氧化鋁鈦雙金屬層的方法來製作二氧化鈦奈米柱陣列並探討其生長機制，主要將陽極氧化處理步驟分為兩階段，第一階段為鋁層陽極氧化，而第二階段為鈦層陽極氧化，並以電流密度1 mA作為分界點。結果發現第一階段施加電壓愈高，二氧化鈦奈米柱的直徑愈大且密度愈小；第二階段施加電壓愈高，奈米柱的成長高度則愈高；而因介電場強度大小的改變，使得其成長速率在初期非常迅速。並藉由光激發螢光光譜發現其光激發螢光波長會因奈米柱表體比不同影響二氧化鈦氧缺陷的多寡，表體比愈大會往長波長移動。且經由崩潰電壓的量測可以發現，經由陽極氧化雙金屬層方法所成長的二氧化鈦奈米柱陣列擁有良好的氣體辨識能力，且可以用於偵測惰性氣體及氧氣方面，並能作為低操作電壓的氣體偵測器。

Recently, the interest to the double-layered anodic oxide arises because of its special applications. It has been reported that a nanostructured anodic oxide can be formed from the underlying metal through the anodic aluminium oxide. And some research indicated that main factor which influence the formation of oxide is the difference of ionic resistivity. In this work, we use anode oxidation to fabricate TiO2 nanorod arrays on a quartz substrate and study their growth mechanism. The anodic process is mainly divided into two parts, anodizing Al layer and Ti layer. The density, diameter and height of the TiO2 nanorods could be controlled by changing the variables of experiment and its growth rate is really fast at the initial stage. From the photoluminescence spectra we could found out that with higher surface area to volume ratio, the PL response will shift to longer wavelengths and the intensity is related to the surface area of the TiO2 nanorods. We also use TiO2 nanorods as the field ionization anode to test the breakdown voltage in different atmosphere. The results show good selectivity and thus they can be used as gas sensors.