應用氧化鋅奈米結構發展創新型表面電漿共振氣體感測晶片

Abstract

表面電漿共振是一種光學式的生物/化學感測器，具有良好的靈敏度、非接觸式、即時反應、及可平行檢測等優點，已在生物分子與化學的檢測元件上成為非常重要之檢定方式。我們的研究是以氧化鋅奈米結構做為一種新式光學氣體檢測裝置之感測層，藉由最佳化之氧化鋅結構與薄膜特性，提供最理想的表面電漿共振曲線與靈敏度，以利未來於一氧化氮氣體檢測之疾病診斷以及環境氣體監視之應用。 本研究中我們以射頻濺鍍系統製作氧化鋅奈米薄膜，由於氧化鋅薄膜其感測效能與其各項薄膜特性皆息息相關，如表面粗糙度、表面晶粒大小、薄膜導電度、光致螢光特性…等，其中薄膜的自由載子濃度與氧化鋅本身之晶格缺陷有關，因此氧化鋅薄膜的感測效能評估將藉由其薄膜電性、螢光特性與表面結構來評估。在物性分析部分，我們利用X光繞射儀、場發射電子顯微鏡與原子力顯微鏡於分析感測薄膜之表面結構與薄膜特性。在螢光特性方面，亦藉由光致螢光光譜儀，分析在不同濺鍍條件下所得的薄膜其光激發光特性，並藉此了解薄膜之缺陷情況。 在本論文實驗中，我們已成功的結合氧化鋅奈米結構於表面電漿共振檢測裝置於一氧化氮氣體之偵測。由薄膜分析實驗結果得知，無氧環境下所沉積之氧化鋅薄膜具有較高比例的氧空缺，進而造成較高之薄膜導電度與較強之綠光發光波段，由氣體感測實驗結果呈現，與此一薄膜特性結合之表面電漿共振氣體感測器已具有快速、可逆反應、低溫以及高靈敏度等良好特性，於未來可望成為一低功率之光學式表面電漿共振氣體感測裝置。

Surface plasmon resonance (SPR) sensing technique, which provides advantages of high sensitivity, non-contact, real-time, and parallel detection, has been developed and played an important role for biomolecular and biochemical sensor. In this study, we proposed to design SPR sensing chip combined with the Zinc Oxide (ZnO) nano-film as a novel optical SPR gas sensor. Depending on the optimal design of ZnO sensing film, it provided better SPR curve and sensitivity and in the future will be able to apply to nitric oxide (NO) detector, which is a critical index in asthma diagnostic, and environmental toxic gas sensor. In this study, we used the radio-frequency sputtering deposition system to prepare the ZnO nano-film. Because the sensing performance of ZnO is intimately related to the physical properties, for instance, the surface roughness, grain size, conductivity, photoluminescence…etc, the study of the electricity and optics as well as morphology are very important and could be the evaluation index for gas sensing performance. The physical characteristics of ZnO thin films were obtained by the analyses of XRD, SEM, and AFM. The optical properties of ZnO thin films with different sputtering parameters were also studied by measuring the photoluminescence spectrometer. In the experiments of this thesis, we have successfully combined the ZnO nano-structure with the SPR sensor to serve as a nitric oxide gas detector. According to the experimental result, it is found that under less oxygen sputtering environment, there is higher extent of oxygen vacancies in the ZnO thin film and, therefore, it has higher conductivity and stronger defect emission at the PL experiment. By combining the oxygen defect ZnO film with SPR, this novel type gas sensor provides several advantages such as fast, reversible, low working temperature and high sensitivity and is able to serve as a low-power required optical surface plasmon resonance gas sensor.