| 摘要: | 本計畫的目的即是針對鍺量子點在前瞻的電子、光電以及光伏元件如:單電子電晶體、光電晶體、彩虹型太陽能電池等進行奠基研究。主要的研究動機是擬利用量子點所擁有的庫倫阻斷效應與量子侷限效應來設計製作創新的元件結構，增進元件的特性品質，以進一步突破傳統光電元件發展的瓶頸，或是創造提出新的奈米光電元件應用。本計畫擬以三年期來進行(1)單電子電晶體、( 2)光電晶體以及(3)太陽能電池等元件的奠基研究。由第一年『單電子電晶體』的研究所開發的量子點成長技術、建構的電子能結構模型、激子與光的交互作用以及載子生命週期的認識，可做為第二、三年研究主題『量子點光電晶體』與『太陽能電池』的元件結構設計以及實作的基石。第二年為提升『量子點光電晶體』的光響應與量子效益擬開發的多層堆疊量子點成長技術，將可延伸作為第三年的研究主題『太陽能電池』所需之三維量子點陣列的製作基礎。經由單電子電晶體與光電晶體的特性解析，所建立的量子點內部激子交互作用以及量子點之間耦合作用的認識，可做為太陽能電池元件結構設計與製程優化的良好基礎。第一年 單電子電晶體我們擬以本實驗室已建立紮實根基的鍺量子點定位定數成長與具自我對準奈米電極製程技術為本，優化其結構設計與製程整合，實作高品質的鍺量子點單電子電晶體。可提供一個良好的測試平台，深入解析量子點內部材料結構特性、電子能結構、電荷/激子態間庫倫交互作用以及暫態量子傳輸行為。主要研究重點分述如下： (1) 實作高品質的量子點單電子電晶體。 (2) 探討流經量子點基態及激發態之穿隧電流。 (3) 探討流經量子點之光電流與光子放射譜線。 (4) 探討流經量子點之時間解析暫態電流與載子生命週期。第二年 鍺量子點光電晶體我們擬以複晶矽薄膜電晶體為本，在閘介電層中加入高密度且大小均勻的鍺量子點堆疊層。鍺量子點吸光層在入射光的照射下，所激發的光電子將穿隧越過薄的氧化層，注入通道之中貢獻導電電荷形成光電流。量子點光電晶體的特性品質如:光響應度、暫態反應速度與(1)量子點的吸光能力(與量子點的結晶性、表面狀態、密度、大小均勻性有關)、(2)光電子/電洞在量子點之間的傳輸能力、(3)吸光區量子點與通道之間穿隧層的位障/厚度及(4)電荷在通道內的遷移率等息息相關。主要研究重點分述如下： (1)開發高密度的鍺量子點堆疊層的成長技術。 (2)設計優化量子點介面設計與暫態響應。 (3)實作高品質的量子點光電晶體。 (4)探討載子在量子點光電晶體內的傳輸機制。第三年矽鍺量子點光伏太陽能電池為增進量子點太陽能電池的轉換效益，我們擬定三種策略以捕獲不同能量的光子，分別是(1)設計製作不同大小的量子點三維陣列，來營造全光譜的直接吸收、(2)利用游離化衝擊與Auger 復合程序，來達成發生多重激子的目標及(3)利用量子點強耦合所生的中間能帶，來分段吸收低能量的光子並激發電子-電洞。主要研究重點分述如下： (1) 發展三維陣列多層次的矽鍺量子點製作技術。 (2) 探討鍺量子點發生多重激子態的條件與載子產生/復合機制 (3) 量子點陣列所致的中間帶 (4) 實作高效率的量子點太陽能電池三年期計畫之研究成果可互相共享，期望多面向地了解開發量子點光電元件的應用。 In this three-year project, we aim to explore cutting-edge fabrication technologies for realizing novel and advanced quantum dot (QD) optoelectronic devices, such as single-electron transistors (SETs), QD photosensitive transistors (PTs), and rainbow solar cells. In addition, we will engage in a deep understanding of QD mesoscopic electricallyand optically driven quantum transports as well as quantum optical effects, which are fundamental but very crucial for QD nano-optoelectronics from functional prototypes into the realm of real application. Motivation to employ QDs in advanced optoelectronic devices is strong in light of its distinctive features of quantum confinement and Coulomb blockade effects. Accordingly we intend to make progresses in the innovation of device functionalities, the improvement of device performance, and even the breakthrough of traditional fabrication bottlenecks and classical physical limitation if possible. The research scheme of this three-year project is proposed to be as follows. In the 1st year, we will demonstrate high performance Ge QD SETs by integrating Ge QDs precise placement and self-aligned electrode technologies. A high performance SET would provide a superior test platform for characterizing QD internal structure properties (crystallinity, morphology, strain, and composition), QD electronic structure (charging energy, energy level separation, coupling strength, and oscillator strength), inter-particles Coulomb interactions, as well as steady-state and transient quantum transports wherein. The capability of QD placement and the knowledge of QD basic internal and electronic structures would lay nature cornerstones for the 2nd and 3rd year research themes “QD phototransistors” and “QD solar cells”. The developed high density QD growth technology and the understanding of exxitons Coulomb interactions in the 2nd year will be a natural extension to realm of QD solar cells in the 3rd year. The proposed research themes in each year are: 1st year: Ge QD single electron transistors (1) Demonstrating high performance Ge QD SETs (2) Investigation of steady-state tunneling spectroscopy. (3) Investigation of photoexcited tunneling spectroscopy. (4) Investigation of transient quantum transport and carrier lifetime. 2nd year: Ge QD phototransistors (1) Developing high density Ge QD stacks growth technology (2) Design of QD interface engineering. (3) Demonstratinghigh performance QD phototransistors (4) Investigation of quantum optical effects in QD phototransistors 3rd year: QD solar cells (1) Developing SiGe QD 3D arrays with grading composition and dot size (2) Investigation of carrier generation/recombination and multi-exciton generation (3) Investigation of intermediate band formation between QDs (4) Demonstrating high performance QD solar cells in PIN or MOS structure There are scientific and technologic significances involved in this proposed project. The research of SETs, phototransistors, and solar cells are closely related to quantum optoelectronics, which is a frontier research field. The implementation of SETs, phototransistors, and solar cells demands smart device design, precise QD growth and placement, and process integration, which will become the key technologies for the industry of nano-optoelectronics. 研究期間：10008 ~ 10107 |
