新穎半導體材料於深紫外/白光之元件設計及有機材料之金屬感測器

Abstract

本論文研究內容包括結合氮化鋁鎵與特殊元件結構之新型深紫外光源以及雷射現象探討、二硫化鉬材料製作以及應用上的最新突破、複合生物材料之重金屬檢測技術。我們結合材料特性以及物理製程技術，研發領先時代前沿的光電元件。全文共可分四個主題，詳細摘要如下： １. 超高靈敏度之全有機標籤式銅離子薄膜感測器 精確分析重金屬濃度對我們的生活至關重要，過高濃度的重金屬不論在環境和人類健康方面都會造成不可逆的負面影響。在本章節中，我們開發了一種新的銅離子感測器，它由有機材料構成且具有穩定的彎曲和拉伸性質。新型感測器包括從新鮮福木葉子中提取的葉綠素-a，天然植物纖維以及使用PDMS基板。螢光光譜研究表明，葉綠素-a對Cu（II）離子的敏感性明顯高於其他任何重金屬離子，並且元件靈敏度優於大部分現已發表的Cu（II）離子感測器。我們的實驗結果充分顯示了葉綠素-a對Cu（II）離子的選擇性(專一性)。彎曲和拉伸測試展示出此感測器的出色耐用性，可用於開發相關的軟式元件，且具有即時採樣並分析汗液中Cu（II）濃度的能力。 ２. 組胺酸參雜二硫化鉬量子點之白色發光二極體設計與分析 近年來，量子點發光二極體由於其所具備的各種優異特性，而被廣泛利用在電視液晶螢幕以及各種3C顯示面板上。在本章節中，我們提出了一種利用新的MoS2量子點（QD）設計白色發光二極體（QD-WLED）的概念，並且成功製造以及演示其優異的發光能力。通過微波加熱振動方式將二維MoS2奈米薄片粉碎成更小尺寸的MoS2量子點，其電子態廣泛分佈現象可從激發放光的波長相依特性推斷。值得注意的是，摻雜組胺酸的MoS2量子點表現出非常強的螢光發光，是未摻雜組胺酸MoS2量子點的七倍。大幅增強的發光主要歸因於氮摻雜所形成的受體束縛激子和缺陷的頓化。摻雜組胺酸的MoS2 量子點LED之電致發光（EL）光譜與摻雜組胺酸的MoS2量子點的光致發光光譜呈現一致，主要的發光主峰皆位於約500 nm附近。除此之外，變電流量測結果更顯示了摻雜組胺酸的MoS2量子點白色發光二極體擁有優異穩定性。在Commission Internationale de l'Eclairage色度坐標分析上，MoS2量子點白色發光二極體的發光為（0.30,0.36），表現出固有的寬帶白色發光。基於單一發光材料和低毒性等優異特性，這種過渡金屬二硫化物量子點白色發光二極體可取代含鎘量子點發光二極體，成為下個世代的新型發光元件。 ３. 石墨烯-絕緣體-半導體接面之紫外發光二極體及其應用 發光二極體（LED）是一種可以藝術地結合光與電的元件。在本章節中，我們提出了一種新型石墨烯-絕緣體-半導體（GIS）紫外發光二極體，它的功能及應用包括穩定的電致發光、出色的光偵測能力和經濟快速的元件製作程序。新型GIS紫外LED由AlGaN薄膜、SiO2絕緣層和石墨烯透明電極組成。在順向偏壓下，石墨烯側的電洞藉由量子穿隧的方式傳導到n-AlGaN的價帶邊緣並與導帶中的電子複合以達到電致發光的目的，其具有超過10％的發光效率。值得注意的是，此紫外光二極體的發光波段涵蓋從UV-A到UV-B，因此它在生物醫學，環境保護和公共衛生等多個領域具有巨大的潛在應用價值。此外，我們的GIS紫外LED顯示出優異的紫外光檢測能力和雙面發光特性，可用於發展光通信和多功能光電元件。 ４. 利用表面電漿共振增強安德森局域化之深紫外光雷射現象 無腔(Cavity-Free)雷射具有許多奇特的特性，包括混沌的光子行為、光的局域化現象、寬廣的雷射發射角度和經濟有效率的製程，這些特性使無腔雷射近年來廣受科學以及產業界的關注。然而，在實現其潛在應用之前，仍然有若干挑戰需要克服，包括瞭解其固有的多方向和混亂波動背後的潛在機制，以及可控性。經過二十多年的合作努力，在隨機雷射中安德森局域化的發現提供了解決困難的合理途徑，這使得能夠定制雷射模態的數量並穩定雷射光譜。表面電漿共振是另一個重要的研究課題，這部分已有相當深入的研究並發展相當成熟。眾所周知，表面電漿共振可用於增強光發射以及光散射。在這項研究中，通過整合安德森局域化和表面電漿共振，AlGaN多重量子井表現深紫外雷射現象。我們的研究提供了足夠證據以證明隨機雷射現象的潛在機制，即在無序介質中光束的多次散射可以引發類似於電子安德森局域化的光子行為。此外，金屬納米粒子的表面等離子體共振提供了一種方便的方式來定制安德森局域化，以實現具有較低閾值的穩定的隨機雷射。值得注意的是，深紫外雷射在環境保護和生物醫學工程等許多領域具有巨大的潛在應用價值。

ABSTRACT In this dissertation, we have achieved novel deep-ultraviolet light source/laser action based on newly designed AlGaN combining particular device structures, the fist electrically driven white light emitting diode derived from MoS2, and the heavy metal detection technology. We have combined the material science and fabrication technology to develop leading-edge optoelectronic devices. Our results are classified as four main topics and summarized as follows: 1. All Organic Label-like Copper (II) Ions Fluorescent Film Sensors with High Sensitivity and Stretchability Deep learning and analysis of heavy metal concentration are very crucial to our life, for it plays an essential role in both environmental and human health. In this paper, we developed a new Cu (II) ions sensor made by all organic material with bending and stretching properties. The new sensor consists of chlorophyll-a extracted from fresh leaves of Common Garcinia, plant fiber and with the use of PDMS as a substrate. Fluorescence spectra study shows that chlorophyll-a is significantly much more sensitive to Cu (II) ions than any other heavy metal ions and the device sensitivity outperforms all the Cu (II) ions sensors ever reported. The result fully shows the selectivity of chlorophyll-a toward Cu (II) ions. Bending and stretching tests show that the sensor has an outstanding durability, which can be used to develop accompanying applications, such as real-time sampling and the analysis of Cu (II) concentration specified in athlete's sweat or patients with brain dead and Parkinson’s disease. 2. Electrically Pumped White-Light-Emitting Diodes Based on Histidine-Doped MoS2 Quantum Dots MoS2 quantum dots (QDs)-based white-light-emitting diodes (QD-WLEDs) have been designed, fabricated and demonstrated. The highly luminescent, histidine-doped MoS2 QDs synthesized by microwave induced fragmentation of two dimensional (2D) MoS2 nanoflakes possess a wide distribution of available electronic states as inferred from the pronounced excitation-wavelength-dependent emission properties. Notably, the histidine-doped MoS2 QDs show a very strong emission intensity, which exceeds seven times of magnitude larger than that of pristine MoS2¬ QDs. The strongly enhanced emission is mainly attributed to nitrogen acceptor bound excitons and passivation of defects by histidine-doping, which can enhance the radiative recombination drastically. The enabled electroluminescence (EL) spectra of the QD-WLEDs with the main peak around 500 nm were found to be consistent with the PL spectra of the histidine-doped MoS2 QDs. The enhanced intensity of EL spectra with the current increase shows the stability of histidine-doped MoS2 based QD-WLEDs. The typical EL spectrum of the novel QD-WLEDs has a CIE chromaticity coordinate of (0.30, 0.36) exhibiting an intrinsic broadband white-light emission. The unprecedented and low-toxic QD-WLEDs based on a single light-emitting material can serve as an excellent alternative for using transition metal dichalcogenides (TMDs) QDs as next generation optoelectronic devices. 3. Graphene–Insulator–Semiconductor Ultraviolet Light-Responsive Nitride LEDs for Multi-Applications Light emitting diode (LED) is a device which can combine the light and electricity artistically. In this work, a novel graphene-insulator-semiconductor (GIS) ultraviolet LED is presented, which possesses state-of-the-art multi-purposes, including electroluminescence, outstanding detection performance, and economical fabrication processes. The new GIS ultraviolet LED consists of AlGaN thin film, SiO2 insulating layer, and the graphene transparent electrode. Under a forward bias, the electroluminescence can be induced by the recombination of holes tunneling from graphene into the valence band edge of n-AlGaN and electrons in the conduction band with a high emission efficiency exceeding 10%. Notably, the emission range of our ultraviolet light emitting diodes covers from UV-A to UV-B, which have a great potential application in several areas, spanning from bio-medicine, environmental protection to public health. Besides, our GIS ultraviolet LEDs show an excellent ultraviolet-detecting capability and the dual-side light emission, which can be used in optical communications and for the development of multifunctional optoelectronic devices. 4. Surface Plasmon Resonance Enhanced Anderson Localization for Deep-Ultraviolet Cavity-Free Laser in AlGaN MQWs Cavity-free lasers exhibit many exotic properties, including chaotic behavior, light localization, broad angular emission, and cost-effective fabrication, which enables them to attract both scientific and industrial interests. However, before the realization of their potential applications, several challenges still remain including the underlying mechanism and controllability due to their inherent multi-directional and chaotic fluctuations. Through more than two decades of collaborative efforts, the discovery of Anderson localization in random lasers provides a plausible route to resolve the difficulties, which enables to tailor the number of lasing modes and stabilize the emission spectra. Surface plasmon represents another important research topic, which has been studies quite intensively. It is well-established that surface plasmon resonance can be used to enhance light emission as well as light scattering. In this study, by integrating Anderson localization and surface plasmon resonance, we demonstrate deep-ultraviolet lasing action in AlGaN multiple quantum wells. Our work serves as firm evidence to support the underlying mechanism of random laser action that multiple scattering of a light beam in a disorder medium can induce Anderson localization similar to electron behavior. We also show that surface plasmon resonance of metallic nanoparticles provides a convenient manner to tailor Anderson localization to achieve stabilized random laser action with a lower threshold. Notably, deep-ultraviolet laser action has great potential application in many areas from environmental protection to biomedical engineering.