奈米金屬團簇應用於奈米結構光電元件 與高感度生醫感測紙

Using metallic nanoclusters to develop nanostructured optoelectronic devices and highly sensitive bio-sensors on papers

曾紹欽(Shao-Chin Tseng)

指導教授 ： 陳學禮

國立臺灣大學/工學院/材料科學與工程學研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.02253

摘要

本論文利用侵入式、雷射退火與雷射引發噴射沉積法製作的金屬奈米團簇開發新型一維奈米結構與光學資料儲存媒介及生醫感測試紙。本論文之第一部分是利用奈米金團簇來開發具高密度奈米結構同質矽抗反射層。利用矽基材表面侵入的原子級奈米金團簇在蝕刻中所具有的獨特催化能力，透過控制奈米金團簇的蝕刻時間，可以在矽基板上製作具有特殊均勻超高密度極微小鐘乳石（stalactite）狀的多孔絨化形貌。此特殊高密度極微小的類鐘乳石結構，不同於以往的一維奈米結構長度，此結構在相當淺的深度下，從紫外光至紅外光的範圍內皆呈現了非常低的反射率。同時比較常見濕式製作一維奈米結構的無電鍍蝕刻之奈米線結構以及自組裝觸媒蝕刻的奈米多孔結構。發現觸媒侵入式蝕刻的鐘乳石結構在蝕刻5分鐘的抗反射效果(300-1000nm平均小於2%)，遠優於自組裝觸媒蝕刻(20分鐘)與無電鍍蝕刻(30分鐘)的時間。換句話說即侵入式觸媒具有比自組裝觸媒與無電鍍的觸媒更佳的催化特性。此較佳的催化特性應是來自於侵入式的觸媒其原子級的尺寸具有更大的催化接觸面積所造成。除此之外，進一步討論奈米鐘乳石結構的場發射特性。我們比較奈米線與鐘乳石結構的場發射特性，發現鐘乳石結構的場發射起始電壓明顯小於結構較大的矽奈米線起使電壓。
在本論文的第二部份，利用奈米金團簇及金屬薄膜蝕刻與保護區域的選擇性，設計光學儲存媒介的應用。研究透過KrF準分子雷射誘發金屬薄膜發生型態轉變為粒子的光熱效應，並設計了一種全新光學資料永久儲存媒介。一般金屬材料在紫外光波段的本質吸收遠高於紅外光波段吸收。因此可利用金屬在深紫外光的高吸收轉變為熱能的效應，於金屬薄膜擇區退火形成粒子陣列。搭配粒子與薄膜於矽的酸蝕刻中所具有的獨特催化能力與保護效應。利用這個方法，可製作出高對比寬波段永久儲存的光學媒介。此外我們呈現了此光學儲存系統可以具有深次微米解析度的記錄能力，並且可利用紫外光波段來作為讀取工具。更進一步來說，此光學儲存媒介將可開發出一種比傳統藍光DVD光碟高出數倍儲存密度的光儲存媒介。
方便、快速、與準確的檢測化學和生物分子在醫學與環境科學領域中是一個相當重要的發展。許多以奈米金屬粒子為主的檢測方式早已開發出來。但由於當前大多數的製程技術昂貴及複雜，因此以表面電漿共振檢測的晶片無法如常見的石蕊試紙一樣廣泛的在日常生活中使用。因而在本論文的第三部份研究中，我們提出了一個方便和實用的技術，以光熱效應為基礎製造表面電漿檢測試紙。這種製程技術優於其他已報導的化學製程方法，具有快速的製程時間（幾秒鐘），大面積輸出量，選擇性的定位，並可在各式紙張基材上製作出高密度的奈米粒子陣列。此外試紙除了成本低，便攜性，靈活性，和可生物分解等優勢外，也可於檢測傳染性的物質後燒毀，具有安全與不汙染的環境友善特性。
在第四部份的研究中，我們提出了一種可控制密度與粒徑大小的雷射引發噴射沉積奈米粒子的方法。利用空氣阻力的效應，控制不同的接收距離可調變奈米粒子粒徑大小從5 nm到50 nm。並進一步計算奈米粒子粒徑大小與噴射沉積距離因空氣阻力之間的關係。 此外，這種方法是適用於製備奈米粒子陣列於各種基材，如矽，玻璃，塑料和紙張基板。同時具有快速、大面積、容易控制粒徑，位置選擇性的優勢。 最後我們利用這種方法製備大粒徑的奈米粒子陣列，用於表面增強拉曼散射（SERS）的樣品。另一方面，我們也製備了小粒徑的奈米粒子陣列作為金屬輔助催化蝕刻的應用，建構一個矽基材的寬波段低反射奈米結構。

關鍵字

奈米糰簇 ； 奈米粒子 ； 一維奈米結構 ； 表面電漿共振

並列摘要

The purpose of this study is using metallic nanoclusters (NCs) and nanoparticles (NPs) to develop one-dimensional nanostructures, optical storage medium and biosensing test papers. In the first part of this thesis, we use NCs to develop antireflection structure performed by unique Si structures of ultrahigh density and very narrow diameter (ca. 10 nm). By using intruded “atomic-scale” Au NCs which are highly active catalysts within Si wafers during etching, we are capable to produce Si nano-stalactite (SNS) structures of ultrahigh density via controlling etching time. The SNS structures of ultrahigh density and shallow depth, which are different from one-dimensional nanostructures reported before, appear quite low reflectance from ultraviolet (UV) to near-infrared (NIR) regime. We find the intruded metallic NCs are more catalytic than self-assembled NPs and electroless-deposited metal catalysts. The better performance comes from larger contact area of intruded NC catalysts because of its atomic-scale size. Furthermore, we discuss the field emission property of the SNS structure. By comparing field emission properties between nanowire and SNS structure, we find that the turn-on field of SNS structure (9.5V/μm) is far less than that of nanowire (18V/μm).
In the second part of this thesis, we design an optical storage medium and its application by using Au NP as etching area and Au thin film as protective area. First, we study the photothermal effect induced by KrF excimer laser illumination, which induces metal thin film to transform into particles. This laser-induced photothermal effect is use to design a brand new optical permanent storage medium. Absorbance of common metal in UV regime is much higher than that in infrared regime. Thus, particle array can be formed by annealing process in selected area on metal thin film where the absorbed energy of metal in deep-UV (DUV) regime transform into heat. Combining unique catalytic ability of NPs and protective thin metal film on Si substrate, a further etching process can thus fabricate a high contrast, broad band and long-lasting optical storage medium. Besides, we display that this optical storage system can record data with sub-micrometer resolution and can be read out by DUV. And this optical storage medium can store several times denser than conventional blu-ray digital video disc (DVD).
Convenient, rapid, and accurate detection of chemical and biomolecules would be a great benefit to medical, pharmaceutical and environmental science. Many chemical and biosensors based on metal NPs have been developed. However, as a result of the inconvenience and complexity of most of the current preparation techniques, surface plasmon–based test papers are not as common as, for example, litmus paper, which finds daily use. In this paper, we propose a convenient and practical technique—based on the photothermal effect—to fabricate the plasmonic test paper. This technique is superior to other reported methods for its rapid fabrication time (a few seconds), large-area throughput, selectivity in the positioning of the NPs, and the capability of preparing NP arrays in high density on various paper substrates. In addition to their low cost, portability, flexibility, and biodegradability, plasmonic test paper can be burned after detecting contagious biomolecules—making them safe and eco-friendly.
In the fourth part of this thesis, we developed a new method—based on laser-induced jets of nanoparticles (NPs) and air drag forces—to select the particle size and density of NP arrays. We then exploited air drag forces to select NPs with sizes ranging from 5 to 50 nm at different captured distances. We further calculated the relationship between the air drag force and the diameter of the NPs to provide good control over the NP size by varying the capture distance. Laser-induced jets of NPs could also be used to fabricate NP arrays on a variety of substrates, including Si, glass, plastic, and paper. This method has the attractive features of allowing rapid, large-area preparation, with ready control over particle size, and with high selectivity in the positioning of NP arrays. In the last, we used this method to prepare both large NP arrays, to act hot spots on surface-enhanced Raman scattering–active substrates, and small NP arrays, to act as metal catalysts for constructing low-reflection, broadband light trapping nanostructures on Si substrates.

並列關鍵字

nanoclusters ； nanoparticles ； one-dimensional nanostructures ； localized surface plasmon resonance

參考文獻

1. G. Schmid, Chem. Rev. 1992, 92 (8), 1709.

2. W. X. Zhang, J. Nanopart. Res. 2003, 5 (3-4), 323.

3. W. Fritzsche, T. A. Taton, Nanotechnology 2003, 14 (12), R63.

6. Z. C. Wang, G. Chumanov, Adv. Mater. 2003, 15 (15), 1285.

8. B. Tian, X. Zheng, T. J. Kempa, Y. Fang, N. Yu, G. Yu, J. Huang, C. M. Lieber, Nature 2007, 449 (7164), 885.