以蜂窩狀結構之氧化銦製備超高靈敏二氧化氮氣體感測器

Abstract

在本篇研究中，我們利用陽極氧化鋁作為模板，製造出一個蜂窩格子狀結構的半導體材料－氧化銦，由於其結構具有規律的孔洞性以及高深寬比的特性，讓我們可以將之應用於氣體的感測。在之前有關這方面的研究，大多是利用奈米線或是薄膜顆粒來作感測，而其製作過程多半是在高溫下的VLS法，步驟不但複雜費時且需使用大型的機台，對氣體的偵測也需在一定溫度下才有反應，更重要的是，大多數的偵測靈敏度都不夠低，因此我們用最簡單的溶膠-凝膠法來製作我們的偵測元件，伴隨陽極氧化鋁的模板所生成的氧化銦孔洞結構，來對二氧化氮這種有害性氣體作感測。在常溫下的量測結果也顯示，不但有良好的靈敏度，快速的可回復時間與重複性，更重要的是，偵測極限亦比目前發表過的研究還低。 我們提出了一個不同於以往的偵測機制：藉由氧空孔的修補來提升導電性。藉由氧電漿的修飾，對導電性有顯著性的增強已被證實，我們亦利用此法來說明我們的偵測機制。像這樣的感測元件，希望在日後能經由表面分子的修飾或是元素的掺雜，能發展成一套電子鼻系統。

We propose a for metal oxide material based on In2O3 honeycomb structure by using anodic aluminum oxide as template. The advantage of the proposed regular structure and high surface-to-volume ratio is beneficial for the gas sensing. Actually, gas molecules sensing plays a crucial role in environmental safeguard, medical diagnosis, and even space exploration. A variety of materials have extensively been ultilized in gas sensing of which In2O3 is a promising material for specific detection of NOx. In previous reports, metal-oxide-semiconductor gas sensors, having a high sensitivity for the detection of both reducing gases and oxidizing gases, are always fabricated in the form of thin films, nanowires, and nanotube. However, using vapor-liquid-solid (VLS) growth always suffers from several problems of poor connection, and uncompatible with unindustrial fabrication. In this study, we propose the self-aligned indium oxide honeycombed nanostructure under porous anodic alumina (PAA) template by sol-gel method. After electrode deposition, honeycombed In2O3 nanostructure is served as the sensing channel to detect NO2 in real-time which reveals not only great sensitivity but also fast recovery time, and more importantly the ultrasensitivity than previous publication under room temperature. Furthermore, we propose a defect-repaired theory to explain the sensing mechanism of our device which is quite than literature’s difference single-crystal nanowires. This approach without tedious process demonstrates a great potential in ultrasensitive gas sensing. In the future, we suspect that we will establish an electronic nose system by element doping or surface modification to recognize various gases.