臺灣博碩士論文加值系統

本論文的主要研究目的為改善大面積氮化鎵發光二極體光輸出功率。在氮化鎵發光二極體中，電流易由p型厚電極注入多重量子井， 而在電極下方所發出的光，容易被電極遮蔽或反射進而被材料所吸收，造成光輸出功率的損失。在本論文中，利用活性離子蝕刻機以三氯化硼氣體在p型金屬電極下方蝕刻出適當深度之凹槽，再將二氧化矽濺鍍於凹槽底部，以杜絕電流向下導通而形成較佳的電流分散特性，當蒸鍍完p型厚電極於此區域後，電流在向凹槽側壁擴散可有效解決電流在正負電極間走最短路徑的擁塞現象而達到電流分布均勻、減低熱效應，進而提高發光效率。
利用CCD照相來觀察發光二極體發光分佈狀況，可證明以三氯化硼蝕刻適度深度的凹槽，再以二氧化矽於底部絕緣的方法，可使發光二極體的光電特性獲得改善。

The purpose of this research is to improve the light output power of high-power light emitting diodes (LEDs), we try to improve the current crowding phenomenon and obtain better optical and electrical properties. The efficiency of output power will reduce because of the light below the p-pad will be eclipsed or reflected by the p-type thick metal electrode. We use the concept of current blocking layer (CBL) to decrease the injection current beneath the p-type thick metal electrode and enhance the efficiency of light output power further. On the other hand, the current crowding will occur because of the beeline in two pads. We dig a fillister structure below the p-pad region by using reactive ion etching (RIE) system and deposit thin silicon oxide on the bottom of the fillister for insulator and avoiding the leakage current increasing. We expect the injection current spreading to the sidewalls of the fillister initially to solve the problem of the current crowding, and reduce the heat effect then improving the efficiency better.
In addition to the optical and electrical properties of the LEDs, we use the CCD system to photograph the luminescence distribution of the LEDs and prove the improvement of the uniform current spreading by digging a fillister with proper depth using BCl3 plasma and make the bottom insulating by depositing thin SiO2.

Abstract (Chinese) I
Abstract (English) II
Acknowledgement IV
Contents V
Table Captions VII
Figure Captions VIII
Chapter1 Introduction
1-1Introduction 1
Reference 4
Chapter2 Experimental Theory
2-1 Theory of Metal-Semiconductor contact 5
2-1-1 P-type ohmic contact 5
2-1-2 N-type ohmic contact 5
2-2 The Equivalent Circuit Model of Uniform Current spreading 6
2-3 Current Crowding Effect in LEDs on Insulating Substrates 7
Reference 11
Chapter3 LED Structure and Experimental Process
3-1 The Structure of LED 12
3-2 Structure Design 12
3-3 Design Charts of masks 13
3-4 The Fabrications of LEDs Chips 14
3-4-1Activation 14
3-4-2 Cleaning Wafer 15
3-4-3 Etching Mesa 15
3-4-4 selective p-type GaN region etching 15
3-4-5 N-type ohmic contact 17
3-4-6 P-type ohmic contact 18
Reference 33 Chapter4 Measurement and Results
4-1 Current-Voltage characteristics 34
4-2 Current-Voltage characteristics (leakage current) 34
4-3 Light Output Power-Current (L-I) characteristics 35
4-4 The Luminescence Distribution captured by CCD 36
Reference 51
Chapter5 Conclusions
5-1 Conclusions 55

Chapter 1
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