藍光雷射實驗室簡介與藍光發光二極體之設計、 模擬、與分析 郭艷光Yen-Kuang Kuo 彰化師大物理系暨光電科技研究所教授 國立彰化師範大學理學院院長 電子郵件: ykuo@cc.ncue.edu.tw 網頁: http://ykuo.ncue.edu.tw

郭艷光 – 藍光雷射實驗室 1997年12月底向彰化師大校長提出「藍光雷射計畫」，提議研發半導體雷射，獲得800萬元經費補助，成立「藍光雷射實驗室」。 除了半導體雷射之外，還帶領學生從事發光二極體(LED)、有機發光二極體(OLED)、太陽能電池(Solar Cell)的研究工作。

實驗室主要的研究能量 本實驗室早期之研究主要利用光激螢光法與電激螢光法來研究半導體雷射(LD)與發光二極體(LED)等光電半導體材料之光學與電子特性。此外，本實驗室之光學系統亦可量測穿透/吸收/反射光譜與拉曼光譜。 在光電實驗之外，我們也並行從事雷射二極體、發光二極體、有機發光二極體(OLED)、與太陽能電池的數值模擬與分析，使用的軟體包括LASTIP、PICS3D、APSYS、SimuLED、SimuLAMP等。 目前研究主要以『系統設計與模擬分析』為主。

實驗室主要的軟體資源 LASTIP模擬軟體 (側射型半導體雷射 …) (Crosslight Software Inc., Canada) PICS3D模擬軟體 (面射型半導體雷射、DFB雷射、Self-Pulsation雷射 …) (Crosslight) APSYS模擬軟體 (LED、 OLED 、太陽能電池、RC-LED、光偵測器、HEMT …) (Crosslight) SimuLED模擬軟體 (LED及LD元件特性，由俄羅斯STR Group公司提供，台灣皮托科技代理) SimuLAMP模擬軟體 (LED等發光元件之封裝，由俄羅斯STR Group公司提供，台灣皮托科技代理)

實驗室主要的硬體設備 光學桌 (2台) 氦氖雷射 (632.8nm紅光光源) 氬離子雷射 (488nm藍光, 514.5nm綠光, 351.1nm紫外線光源) Nd:YAG雷射 (EO Q-switched, 1064/532/355/266 nm) 單色分光儀與鹵素燈寬頻光源 (穿透, 吸收, 反射頻譜測量) 波長選擇器 (Birefringent Filter) 發光二極體(LED/OLED)亮度與I-V特性測量儀 (PC-controlled) 半導體雷射/發光二極體電流源 (PC-controlled current source) 密閉式低溫系統 (10K ~ 325K) 液態氮冷卻電荷耦合器(CCD)光偵測器 (1340×100 Pixels) 鎖相放大器 (Lock-in Amplifier) 光電增倍管 (Photo-Multiplier Tube) 功率計 (Power Meters) (3組) 半導體摻雜濃度測量儀 (ECV, 適用於GaN系統) 快速示波器 (500 MHz Bandwidth, 5 GHz Sampling Rate) 快速光偵測器 (Response time ~ 1 ns)

光激螢光(Photoluminescence)系統簡介 波長為351.1 nm, 488.0 nm, 514.5 nm, … 低溫系統： 10 K ~ 325 K 光纖 控制 相位截光器 氬離子雷射 待測元件 光電增倍管 鎖相放大器 CCD (Princeton) 電腦 穿透量測入口 單色分光儀(ARC SP-750)

郭艷光開設之研究所課程 99(上)授課內容： 99(下)預定授課內容： (1) 半導體光學 (物理系與光電所碩博合開選修) (2) 半導體雷射特論 (物理系與光電所碩博合開選修) 99(下)預定授課內容： (1) 半導體雷射 (物理系與光電所碩博合開選修) (2) 發光二極體特論 (物理系與光電所碩博合開選修)

同學們離開學校之前，必須具備： 專業、英語、電腦網路三項重要能力

成功的秘訣： 要有好的人格特質！ 有時候， 吃虧就是佔便宜。

及早規劃人生，船到橋頭自然直的觀念可能會讓你辛苦一輩子

高學位、名校不再是生活的保障，實力決定一切！

學術能力強、具獨立研究能力的人到台清交成進修，可能可以得到超乎常人的成就； 研究所的訓練，關鍵在指導教授。留下來彰化師大唸碩士班、博士班，說不定可以得到更好的訓練。

申請大專生國科會計畫需要有好成績做後盾，留下來唸碩士班、博士班不需要考慮成績好壞，只要肯拼，每個人都會有屬於自己的一片天空。

直攻光電科技研究所與物理研究所博士班的資格： (1) 碩士班一年級學生， (2) 大學部四年級學生。 註：國科會千里馬計畫可以提供獎學金給優秀博士生至國外大學進修。

如果你對發光二極體(LED)、OLED、半導體雷射、太陽能電池的研發有興趣，歡迎你(妳)加入藍光雷射實驗室的大家庭！

國科會專題與產學合作計畫 三五族與氮化物光電半導體元件之實驗及模擬分析(1/3) (NSC 99-2119-M-018-002-MY3) 高效率藍光與近紫外光InGaN LED之模擬與設計 (晶元光電股份有限公司合作計畫) 氮化鋁鎵深紫外光發光二極體元件之模擬分析與設計 (99年大專學生參與國科會專題研究計畫，NSC 99-2815-C-018-008-M)

近年來主要的研究主題 Light-Emitting Diodes (LED) Laser Diodes & VCSEL Light-Emitting Diodes (OLED) Solar Cells (Si & III-V) Others (III-N Band Structures & Bowing Parameters, Solid-State Lasers, etc.) (數篇SCI論文被引用數在10次以上)

模擬軟體在學術與產業上的應用 模擬軟體可以協助研究人員設計元件，並且探討元件的光學與電子特性。 如果有實驗結果可以進行比較分析，我們通常會調整可用的Free Parameters，讓模擬結果可以盡可能與實驗結果一致。 接下來，我們可以提出各種可以改善元件特性或操作性能的方法，進行模擬分析。 經過幾次的調整與校正之後，模擬軟體即可成為元件設計的重要輔助工具，既可省下大量嘗試錯誤的時間，並能節省研發經費，取得研發與量產的先機。

APSYS模擬軟體 (Advanced Physical Models of Semiconductor Devices) LED、OLED、與Solar Cell等光電半導體元件的設計、模擬、與分析，均可以借助APSYS模擬軟體來執行。 APSYS可以經由解Poisson’s equation、current continuity equation、carrier energy transport equation、以及quantum mechanical wave equation等方程式，求得光電半導體元件的各種光學與電子特性。 APSYS亦使用Ray-Tracing技術，分析由元件所輸出之光強度以及光場隨角度之分佈情形。

APSYS所能提供的資訊 光功率-電流(L-I)與電流-電壓(I-V)圖 電位、電場、電流分佈圖 電子、電洞濃度分佈圖 元件溫度分佈圖 不同溫度、電流下之能帶圖 二維光場分佈圖 自發輻射頻譜對電流關係圖 以上所有圖形對時間的變化關係 以上所有圖形對溫度的變化關係

Examples of Simulations Simulation of LEDs Simulation of Laser Diodes Simulation of VCSELs Simulation of OLEDs Simulation of Solar Cells

Simulation of LEDs

After comparing, preferable designs of the staggered QWs are In0.20Ga0.80N (1.4 nm)–In0.26Ga0.74N (1.6 nm), In0.21Ga0.79N (1.4 nm)–In0.25Ga0.75N (1.6 nm), and In0.22Ga0.78N (1.5 nm)–In0.24Ga0.76N (1.5 nm), which are named as structure A, structure B, and structure C, respectively.

The effective potential height for holes in the valence band of the InGaN/AlGaN structure is lower than that of the InGaN/GaN one (i.e., 0.255 eV vs. 0.282 eV) owing to the slighter polarization effect in the last-barrier/EBL interface. The effective potential height for the electrons in the conduction band of the InGaN/AlGaN structure becomes higher than the other structure (i.e., 0.367 eV vs. 0.355 eV), which denotes the enhancement of electron confinement.

The light performance of the blue InGaN LEDs emitting in a spectral range from 435 to 445 nm can be enhanced effectively when the conventional GaN barrier layers are replaced by the low-indium-content In0.02Ga0.98N and In0.05Ga0.95N barrier layers. The light performance of the 445-nm LEDs with the In0.05Ga0.95N barrier layers is improved due to the increased overlap of electrons and holes inside the QW close to the p-side layers, which is the major source for radiative recombination.

The strong electric field caused by the piezoelectric polarization charges at the interface between the P-AlGaN and barrier layer lowers the conduction band energy in the last barrier. Our calculation shows that the percentages of electron leakage current for the LEDs with P-AlGaN and N-AlGaN are 46.1% and 4.5%, respectively, at 120 mA. Besides the relatively uniform distribution of holes in the QWs, the sufficiently reduced electron leakage current is also a major cause for the improvement in efficiency droop.

Simulation of Laser Diodes

Simulation of VCSELs

Simulation of OLEDs

Simulation of Solar Cells

太陽能電池的模擬與分析 Investigation of current matching for In0.49Ga0.51P/GaAs/Ge triple-juction tandem solar cell Band diagram Schematic drawing of the solar cell structure

上中下三個Cells的I-V曲線 Device current is limited by the smallest current.

中間Cell的最佳厚度 … … 3.8 µm Change the thickness of middle cell base layer. Change the thickness of middle cell emitter layer when the base layer thickness is fixed at 3.8 µm.

上中兩個Cells的電流匹配 Sun light power decay 0.236 µm Sun light power at top cell decay Sun light power at middle cell Base layer thicknesses of middle cell → 3.8 μm Emitter layer thicknesses of middle cell → 0.17 μm Base layer thickness of top cell → 0.236 μm

優化後的結構 The photon current density of the device can be improved by enhancing the middle cell photon current density. Schematic drawing of optimized structure

太陽能電池模擬與分析的結論 The short-circuit current density is improved due to the achievement of current match. The short-circuit current density is improved from 16.56 to 18.78 mA/cm2 and the conversion efficiency is increased by about 3%. improved about 3%

Recent publication (I) Yen-Kuang Kuo, Jih-Yuan Chang, and Miao-Chan Tsai, “Enhancement in hole injection efficiency of blue InGaN light-emitting diodes from reduced polarization by some specific designs on electron blocking layer”, Optics Letters, Accepted 4 September 2010. (SCI) [2008 Impact Factor = 3.772, Ranked 4/64 in Optics] Chih-Teng Liao, Miao-Chan Tsai, Bo-Ting Liou, Sheng-Horng Yen, and Yen-Kuang Kuo, “Improvement in output power of a 460-nm InGaN light-emitting diode using staggered quantum well”, Journal of Applied Physics, Accepted 8 July 2010. (SCI) [2008 Impact Factor = 2.201, Ranked 20/95 in Physics, Applied Physics] Yen-Kuang Kuo, Syuan-Huei Horng, Miao-Chan Tsai, Sheng-Horng Yen, and Shu-Hsuan Chang, “Effect of normal and reversed polarizations on optical characteristics of ultraviolet-violet InGaN laser diodes”, Optics Communications, Vol. 283, Issue 19, pp. 3698–3702, 1 October 2010. (SCI) [2008 Impact Factor = 1.552, Ranked 23/64 in Optics] Jih-Yuan Chang, Miao-Chan Tsai, and Yen-Kuang Kuo, “Advantages of blue InGaN light-emitting diodes with AlGaN barriers”, Optics Letters, Vol. 35, No. 9, pp. 1368–1370, 1 May 2010. (SCI) [2008 Impact Factor = 3.772, Ranked 4/64 in Optics]

Recent publication (II) Yen-Kuang Kuo, Miao-Chan Tsai, Sheng-Horng Yen, Ta-Cheng Hsu, and Yu-Jiun Shen, “Effect of p-type last barrier on efficiency droop of blue InGaN light-emitting diodes”, IEEE Journal of Quantum Electronics, Vol. 46, No. 8, pp. 1214–1220, August 2010. (SCI) [2008 Impact Factor = 2.413, Ranked 37/229 in Engineering, Electrical & Electronic] Miao-Chan Tsai, Sheng-Horng Yen, and Yen-Kuang Kuo, “Carrier transportation and internal quantum efficiency of blue InGaN light-emitting diodes with p-doped barriers”, IEEE Photonics Technology Letters, Vol. 22, No. 6, pp. 374–376, 15 March 2010. (SCI) [2008 Impact Factor = 2.173, Ranked 12/64 in Optics] Jun-Rong Chen, Yung-Chi Wu, Shih-Chun Ling, Tsung-Shine Ko, Tien-Chang Lu, Hao-Chung Kuo, Yen-Kuang Kuo, and Shing-Chung Wang, “Investigation of wavelength-dependent efficiency droop in InGaN light-emitting diodes”, Applied Physics B: Lasers and Optics, Vol. 98, No. 4, pp. 779–789, March 2010. (SCI) [2008 Impact Factor = 2.167, Ranked 13/64 in Optics] Yen-Kuang Kuo, Syuan-Huei Horng, Sheng-Horng Yen, Miao-Chan Tsai, and Man-Fang Huang, Published online 26 November 2009, “Effect of polarization state on optical properties of blue-violet InGaN light-emitting diodes”, Applied Physics A: Materials Science & Processing, Vol. 98, No. 3, pp. 509–515, 4 January 2010. (SCI) [2008 Impact Factor = 1.884, Ranked 30/95 in Physics, Applied Physics]

Recent publication (III) Yen-Kuang Kuo, Jih-Yuan Chang, and Mei-Ling Chen, “Role of electron blocking layer in III-nitride laser diodes and light-emitting diodes”, Proceedings of SPIE, Vol. 7597, pp.759720-1–759720-9, Published online 25 February 2010. (EI) Shu-Hsuan Chang, Miao-Chan Tsai, Sheng-Horng Yen, Shu-Jeng Chang, and Yen-Kuang Kuo, “Numerical simulation on high-efficiency GaInP/GaAs/InGaAs triple-junction solar cells”, Proceedings of SPIE, Vol. 7597, pp.759721-1–759721-12, Published online 25 February 2010. (EI) 陳俊榮、張誌原、郭艷光、盧廷昌、郭浩中、王興宗, “高亮度氮化鎵發光二極體：高驅動電流下的屏障”, 電子月刊, 第16卷, 第6期, 第118至129頁, 2010年6月. Yen-Kuang Kuo, Jih-Yuan Chang, Miao-Chan Tsai, and Sheng-Horng Yen, “Advantages of blue InGaN multiple-quantum well light-emitting diodes with InGaN barriers”, Applied Physics Letters, Vol. 95, No. 1, pp. 011116-1 - 011116-3, Published online 10 July 2009. (SCI) [2008 Impact Factor = 3.726, Ranked 10/95 in Physics, Applied Physics] Yen-Kuang Kuo, Miao-Chan Tsai, Sheng-Horng Yen, Ta-Cheng Hsu, and Yu-Jiun Shen, “Enhancement of light power for blue InGaN light-emitting diodes by using low-indium-content InGaN barriers”, IEEE Journal of Selected Topics in Quantum Electronics, Vol. 15, No. 4, pp. 1115-1121, 5 August 2009. (SCI) [2008 Impact Factor = 2.518, Ranked 9/64 in Optics]

Recent publication (IV) Yen-Kuang Kuo, Miao-Chan Tsai, and Sheng-Horng Yen, “Numerical simulation of blue InGaN light-emitting diodes with polarization-matched AlGaInN electron-blocking layer and barrier layer”, Optics Communications, Vol. 282, Issue 21, pp. 4252-4255, 1 November 2009. (SCI) [2008 Impact Factor = 1.552, Ranked 23/64 in Optics] Sheng-Horng Yen, Miao-Chan Tsai, Meng-Lun Tsai, Yu-Jiun Shen, Ta-Cheng Hsu, and Yen-Kuang Kuo, “Effect of n-type AlGaN layer on carrier transportation and efficiency droop of blue InGaN light-emitting diodes”, IEEE Photonics Technology Letters, Vol. 21, No. 14, pp. 975-977, 15 July 2009. (SCI) [2008 Impact Factor = 2.173, Ranked 12/64 in Optics] Sheng-Horng Yen, Miao-Chan Tsai, Meng-Lun Tsai, Yu-Jiun Shen, Ta-Cheng Hsu, and Yen-Kuang Kuo, Published online 26 June 2009, “Theoretical investigation of Auger recombination on internal quantum efficiency of blue light-emitting diodes”, Applied Physics A: Materials Science & Processing, Vol. 97, Issue 3, pp. 705-708, 4 November 2009. (SCI) [2008 Impact Factor = 1.884, Ranked 30/95 in Physics, Applied Physics] Miao-Chan Tsai, Sheng-Horng Yen, Shu-Hsuan Chang, and Yen-Kuang Kuo, “Effect of spontaneous and piezoelectric polarization on optical characteristics of ultraviolet AlGaInN light-emitting diodes”, Optics Communications, Vol. 282, Issue 8, pp. 1589-1592, 15 April 2009. (SCI) [2008 Impact Factor = 1.552, Ranked 23/64 in Optics]

Recent publication (V) Jun-Rong Chen, Yung-Chi Wu, Tien-Chang Lu, Hao-Chung Kuo, Yen-Kuang Kuo, and Shing-Chung Wang, “Numerical study on lateral mode behavior of 660-nm InGaP/AlGaInP multiple-quantum-well laser diodes”, Optical Review, Vol. 16, No. 3, pp. 375–382, Published online 9 June 2009. (SCI) [2008 Impact Factor = 0.545, Ranked 51/64 in Optics] Yen-Kuang Kuo, Ying-Chung Lu, Miao-Chan Tsai, and Sheng-Horng Yen, “Numerical simulation of 405-nm InGaN laser diodes with polarization-matched AlGaInN electron-blocking layer and barrier layer”, Proceedings of SPIE, Vol. 7211, 72111B-1 – 72111B-8, January 2009. (EI) Bo-Ting Liou, Miao-Chan Tsai, Chih-Teng Liao, Sheng-Horng Yen, and Yen-Kuang Kuo, “Numerical investigation of blue InGaN light-emitting diodes with staggered quantum wells”, Proceedings of SPIE, Vol. 7211, pp. 72111D-1 – 72111D-8, January 2009. (EI) Shu-Hsuan Chang, Chien-Yang Wen, Yi-Hsiang Huang, and Yen-Kuang Kuo, “Numerical simulation on white OLEDs with dotted-line doped emitting layers”, Proceedings of SPIE, Vol. 7213, 72131J-1 – 72131J-8, January 2009. (EI)

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