The Application of Indium Tin Oxide Conductive Layer for AlGaInP LEDs 盧俊宇、蕭宏彬
E-mail: [email protected]
ABSTRACT
Indium-Tin Oxide, was introduced to enhance the current spreading and been a transparent electrode. ITO is widely used on electro optical devices due to its high conductance (ρ=2.5×10-4Ω cm) and superior transparency (>90%). On a conventional AlGaInP LED, it is hard to form a good ohmic contact between ITO and GaP window layer. In order to resolve this issue, we formed a Ni/ITO layer on GaP to obtain a good ohmic contact in this study.
In this work, a Ni(6 nm)/ITO(230 nm) layer was deposited onto the AlGaInP LED by an electron beam evaporation system, then we measured the sheet resistance and transmittance.The transmittance of Ni/ITO layer can reach 91% at 630nm in this experiment.
The Ni/ITO layer, annealed in a furnace at 450℃ under air ambient for 15 min, is found to achieve the lowest sheet resistance. We regard the Ni/ITO layer as a contact layer of window layer of AlGaInP LEDs for application, the drive voltage, drop of about 0.04V and 0.13V at an operation current of 20mA, as compared to the LED with GaP and GaP/ITO structure. The luminous intensity of GaP/Ni/ITO structure LED is 1.23 and 1.62 times higher than that of GaP and GaP/ITO structure LED at an operation current of 100mA. Key Words: ITO, AlGaInP, LEDs.
Keywords : ITO、AlGaInP、LEDs
Table of Contents
封面內頁 簽名頁
博碩士論文暨電子檔案上網授權書………iii
中文摘要………iv
Abstract………v
致謝 ………vi
目錄 ………vii
圖目錄………ix
表目錄………xi
第一章. 緒論………1
1.1 研究背景………1
1.2 化合物半導體材?………2
1.3 發光機制………4
第二章. 理論………11
2.1 P-N接面原?………11
2.2 發光二極體的工作原?………11
2.3 高亮度AlGaInP 發光二極體………12
2.3.1 窗口層(window layer) ………13
2.3.2 電流阻障層 (Current Blocking Layer) …………13
2.3.3 透明導電層(transparent conductive layer) ………14
2.4 氧化銦錫(ITO) ………15
2.5 Ni/ITO薄膜特性………17
第三章. 實驗設備及流程………26
3.1 蒸鍍系統………26
3.2 穿透率量測………26
3.3 發光光強?（L-I）?測………27
3.4 XPS (X-ray Photoelectron Spectroscopy) ………27
3.5 ITO與Ni/ITO薄膜光電特性………28
3.6 LED元件製作………29
3.6.1 試片清潔………29
3.6.2 蒸鍍ITO及Ni/ITO………29
3.6.3 ITO、Ni/ITO退火………30
3.6.4 黃光微影定義P電極區域………30
3.6.5 蒸鍍P電極及N電極………31
3.6.6 PN電極退火………31
第四章. 實驗結果分析………38
4.1 Ni、ITO及Ni/ITO薄膜穿透率分析………38
4.2 Ni、ITO及Ni/ITO薄膜片電阻分析………39
4.3 電壓-電流(I-V) 特性分析………39
4.4 發光強度-電流(L-I)特性分析………41
4.5 XPS縱深成份分析………42
第五章. 結論………53
參考文獻………55 REFERENCES
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