English  |  正體中文  |  简体中文  |  全文筆數/總筆數 : 64745/64745 (100%)
造訪人次 : 20414206      線上人數 : 340
RC Version 7.0 © Powered By DSPACE, MIT. Enhanced by NTU Library IR team.
搜尋範圍 查詢小技巧:
  • 您可在西文檢索詞彙前後加上"雙引號",以獲取較精準的檢索結果
  • 若欲以作者姓名搜尋,建議至進階搜尋限定作者欄位,可獲得較完整資料
  • 進階搜尋


    請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/8894


    題名: 氮化銦鎵量子井與藍紫光雷射二極體結構之成長與分析;Growth and Characterization of InGaN/GaN Quantum Well and Blue-violet Laser Diode Structures
    作者: 卓昌正;Chang-Cheng Chuo
    貢獻者: 電機工程研究所
    關鍵詞: 氮化鎵;氮化銦鎵;氮化鋁鎵;有機金屬化學氣相沈積;量子井結構;雷射二極體;GaN;InGaN;AlGaN;MOCVD;Quantum Well Structure;Laser Diodes
    日期: 2002-06-20
    上傳時間: 2009-09-22 11:37:13 (UTC+8)
    出版者: 國立中央大學圖書館
    摘要: 本論文主旨為成長氮化銦鎵量子井與藍紫光雷射二極體結構,並探討其量子井結構之發光機制、材料熱穩定性、雷射二極體結構特性量測與分析。 首先,我們利用光激光量測方式及理論計算來研究其發光機制。從不同量子井厚度之氮化銦鎵多重量子井結構光激光譜的變化,我們推估當銦含量為 0.23 時,其內建壓電電場將高達 1.92 MV/cm。由於此內建電場的存在,隨著激發光率的提升,其光激光譜呈現一半高寬縮少之藍位移現象。在高激發功率下,其發光波長隨溫度變化行為大致上吻合 Varshini 的經驗公式。然而在低激發光率下,卻可觀察到一 ‘S’ 型變化之光譜圖。因此,我們首先提出一包含光激發載子與熱游離載子電場遮蔽模型來解釋此一特殊現象。光譜均相性與非均相性寬化隨著溫度變化之相互競爭行為亦有深入的探討。另外,我們從發光效率之溫度相依性中觀察到兩個載子逃脫途徑,利用理論計算方式我們確定此載子逃脫途徑分別為激子解離能及電子從量子井能階至位障層所需之能量。 接著,我們藉由熱處理方式搭配光激光譜量測與理論計算來萃取此材料之相互擴散係數。從獲得之單一活化能行為我們推論此材料之相互擴散機制是由空缺次近位置跳躍方式所主導。而在高銦含量 (~40%) 之量子井結構中,藉由熱處理的方式可觀察到相轉變的現象。從橫切面穿透式電子顯微鏡的觀測可發現高銦含量之類量子點結構經過 900 oC熱處理之後其大小與密度均變小。而相對應之光激光譜只剩兩個主要的訊號,其發光來源分別為量子井能階與侷限能態的躍遷所致。從觀察到之史托克位移能量,我們亦間接推論出其量子井中之內建壓電電場將高達 3.2 MV/cm 以上。之外,在短時間熱處理的實驗中,我們觀察到光激光 譜呈現一紅位移再藍位移之現象,此結果和我們在相互擴散實驗中的推論是一致的,我們亦提出三維度擴散模型來描述此材料原子相互擴散之行為。 最後,我們完成氮化銦鎵藍紫光雷射二極體結構之設計、製作與特性分析。雖可以光激方式得到雷射發光,但仍未能獲電激雷射現象,惟從電激光譜中我們發現兩個不同發光行為的訊號。隨著注入電流的增加,低能量訊號產生極大藍位移與光譜寬化現象;反之,高能量訊號出現些微藍位移與光譜窄化情形。此結果驗證了此結構同時具有侷限能態與二維量子井能階躍遷的特性。特別的是,相對於侷限能態躍遷,此二維量子井能階躍遷訊號具有雙激子特性,這將可大幅降低雷射二極體之臨界電流。此外,我們觀察到侷限能態其載子熱逃脫行為具有電流相依性,並提出一多重載子逃脫途徑模型來解釋此一現象。 This dissertation includes the growth and characterization of InGaN/GaN quantum well and laser diode structures grown by metalorganic chemical vapor deposition. The main work can be divided into the following three parts. First, the luminescence mechanism of InGaN/GaN multiple quantum wells (MQWs) is studied using photoluminescence (PL) measurements combined with theoretical calculations. A large piezoelectric field of 1.92 MV/cm is deduced from the well width dependence of PL emission energy for the InGaN/GaN MQWs with In composition of ~0.23. Significant spectral blueshift accompanied by linewidth reduction is observed as increasing the excitation power at low temperature. While the emission energy with temperature follows the empirical Varshini equation under high excitation power, the so-called S-shaped spectral shift is observed under low excitation power. A model, taking into account photogenerated and thermally activated carrier screening effects on the polarization field in the InGaN quantum well, is developed to account for this phenomenon. Competition of inhomogeneous and homogeneous PL linewidth broadening with temperature is discussed. Besides, two carrier loss channels are deduced from the temperature quenching of PL intensity. One is the dissociation of exciton and the other one is the escape of electron from quantum well. Second, the interdiffusion coefficient of In and Ga cations is extracted by self-consistent calculation of diffusion, Schrödinger and Poisson’s equations. The interdiffusion process is characterized by a single activation energy of about 3.4 eV and governed by vacancy-controlled second-nearest-neighbor hopping. Phase transformation in InGaN/GaN MQWs with high indium content (~40%) is observed upon thermal annealing. Cross-sectional transmission electron microscopy shows the existence of quantum dot-like islands within the quantum wells for the as-grown sample but these islands are significantly reduced after thermal annealing at 900 ºC. Two dominant high- and low-energy peaks are assigned to be from the quantum well state and localized state transitions, respectively. A huge piezoelectric field of ~3.2 MV/cm is also deduced from the Stoke shift energy. Besides, the effect of composition inhomogeneity on the luminescence is investigated. The PL peak exhibits a redshift followed by a blueshift with increasing the annealing time. A diffusion model, including the in-plane and out-plane diffusion of In-rich dot-like structures, is proposed to account for the spectral shift. The suppression of phase separation is attributed to the elastic strain in the pseudomorphic InGaN quantum well. Finally, the electroluminescence characteristics of blue-violet laser diode structures are explored. Two emission peaks with different behavior are observed. Significant blueshift and linewidth broadening is measured for the low-energy peak with injection current, while slight blueshift and moderate linewidth narrowing occurs for the high-energy peak. Accordingly, these two peaks are assigned to be from the localized state and quantum well state emissions, respectively. The quantum well state emission exhibits a biexciton feature in contrast to the localized excitons. Besides, the emission associated with the localized state shows injection current dependent thermal quenching behavior. A multiple carrier escaping mechanism is proposed to account for this phenomenon.
    顯示於類別:[電機工程研究所] 博碩士論文

    文件中的檔案:

    檔案 大小格式瀏覽次數
    0KbUnknown884檢視/開啟


    在NCUIR中所有的資料項目都受到原著作權保護.

    社群 sharing

    ::: Copyright National Central University. | 國立中央大學圖書館版權所有 | 收藏本站 | 設為首頁 | 最佳瀏覽畫面: 1024*768 | 建站日期:8-24-2009 :::
    DSpace Software Copyright © 2002-2004  MIT &  Hewlett-Packard  /   Enhanced by   NTU Library IR team Copyright ©   - 回饋  - 隱私權政策聲明