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標題: 磷化鋁銦鎵發光二極體磷化鎵窗口層表面缺陷之改善研究
Improvements of Surface Defects in GaP Window Layers for AlGaInP Light-Emitting Diodes
作者: 沈孟駿
Shen, Meng-Chun
關鍵字: GaP window layer;磷化鎵窗口層;AlGaInP;LED;MOCVD;TMGa;磷化鋁銦鎵;發光二極體;有機金屬化學氣相磊晶法;三甲基鎵
出版社: 精密工程學系所
引用: 【1】G. B. Stringfellow and M. G. Craford,” High brightness light emitting diodes,” Semiconductor & Semimetals, vol. 48, 1997. 【2】K. S. Teng, R. J. Cobley, M. R. Brown and S. P. Wilks,” Investigation on (Al0.7Ga0.3)0.5In0.5P/(Al0.3Ga0.7)0.5In0.5P multi-quantum-barrier superlattice using cross-sectional scanning tunneling microscopy,” J. Appl. Phys. vol. 98, 033525, 2005. 【3】C. Y. Lee M. C. Wu and W. Lin,” The influence of window layers on the performance of 650 nm AlGaInP/GaInP multi quantum-well light-emitting diodes,” J. Crystal Growth. vol . 200, pp. 382-390, 1999. 【4】P. Altieri, A. Jaeger, R. Windisch, N. Linder, P. Stauss, R. Oberschmid and K. Streubel,” Internal quantum efficiency of high-brightness AlGaInP light-emitting devices,” J. Appl. Phys. vol. 98, 086101, 2005. 【5】S. Wicaksono, S. F. Yoon, W. K. Loke, K. H. Tan and B. K. Ng,” Effect of growth temperature on closely lattice-matched GaAs SbN intrinsic layer for GaAs-based 1.3 µm p-i-n photodetector,” J. Appl. Phys. vol. 99, 104502, 2006. 【6】X. B. Zhang, J. H. Ryou, R. D. Dupuis, G. Walter and N. J. Holonyak,” Metalorganic chemical vapor deposition growth and characterization of InGaP/GaAa Superlattices,” J. Electron. Mater. vol. 35, pp. 705-711, 2006. 【7】B. G. Streetman, Solid State Electronic Devices, 4 edition., Prentice-Hall, USA, 1995. 【8】R. M. Fletcher, C. P. Kuo, T. D. Osentowski, K. H. Huang, M. G Craford and V. M. Robbins,” The growth and properties of high performance AlGaInP emitters using a lattice mismatched GaP window layer,” J. Electron. Mater. vol. 20, no. 12, pp. 1125-1130, 1991. 【9】K. H. Huang, J. G. Yu, C. P. Kuo, T. D. Osentowski, L. J. Stinson and M. G. Craford,” Twofold efficiency improvement in high performance AlGaInP light-emitting diodes in the 555-620 nm spectral region using a thick GaP window layer,” Appl. Phys. Lett. vol. 61, pp. 1045-1047, 1992. 【10】C. Asplund, S. Mogg, G. Plaine, F. Salomonsson, N. Chitical and M. Hammar,” Doping-induced losses in AlAs/GaAs distributed Bragg reflectors,” J. Appl. Phys. vol. 90, pp. 794-800, 2001. 【11】P. W. Evans, J. J. Wierer and N. J. Holonyak,” AlxGa1 – xAs native-oxide-based distributed Bragg reflectors for vertical cavity surface emitting lasers,” J. Appl. Phys. vol. 84, pp. 5436-5440, 1998. 【12】Y. Ohba, Y. Nishikawa, C. Nozaki, H. Sugawara and T. Nakanisi,” A study of p-type dopping for AlGaInP grown by low-pressure MOCVD, “ J. Cryst. Growth. vol. 93, pp. 613-617, 1988. 【13】史光國,”現代半導體發光及雷射二極體材料技術”,全華科技圖書出,2001。 【14】史光國,”現代半導體發光及雷射二極體材料技術-進階篇”,全華科技圖書出,2004。 【15】T. Tanaka, S. Minagawa, T. Kawano, and T. Kajimura,” Lasing wavelengths of index-guided AlGaInP semiconductor laser as functions of off-angle from (100)plane of GaAs substrate,” Electron. Lett., vol. 25, pp. 905-907, 1989.
本論文主要探討高亮度磷化鋁銦鎵四元發光二極體結構中之磷化鎵窗口層表面缺陷的形貌,我們採用有機金屬化學氣相磊晶法在成長磷化鎵窗口層,並改變其磊晶成長溫度參數,來觀察其表面缺陷的改善與否。由實驗首先得知,在原本未改變磊晶成長溫度下(650 ℃),磷化鎵窗口層之表面的缺陷過多,此缺陷分佈約佔晶片整體表面積的20~30%左右,是發光二極體磊晶廠急待解決的問題之一。我們觀察此缺陷的形成,推測其形成原因可能是在成長磷化鎵窗口層時,由於磊晶成長溫度的不足,鎵原子無法跟適量的磷原子產生化學反應,造成反應的三甲烷基鎵過多,而直接在氣相當中形成鎵原子掉落在磷化鎵窗口層上,此時當它再吸附磷原子時,就會形成結晶核,然而隨著磊晶成長的持續進行就會演變成團簇,這就是造成缺陷的原因。所以當我們把磷化鎵窗口層之成長溫度提高時,我們發現磷化鎵窗口層表面上的缺陷會隨著磊晶溫度升高而慢慢遞減,最後缺陷分佈約佔晶片整體表面積的5 ~10%左右。從四元發光二極體的元件特性來看,我們發現其發光亮度上有稍微受到影響,在操作電流20 mA下,亮度由原先的90 mcd降至80 mcd,其操作電壓由原先的1.93 V升高至2.03 V左右,推測這應該是磷化鎵窗口層其成長溫度的上升造成鎂攙雜濃度下降。所以在後續的實驗當中,希望能在改善磷化鎵窗口層表面狀況下,也能維持發光亮度和操作電壓的穩定性。

This thesis describes the improvements of surface defects in the GaP window layer on the top of the high-brightness AlGaInP-based light-emitting diode (LED) using metalorganic chemical vapor deposition (MOCVD). As the deposition temperature kept at 650°C, the GaP window layer appeared so many surface defects, which were widely distributed all over the epi-wafer for about 20~30%. This could be due to the low deposition temperature, yielding insufficient phosphorus atoms in the gas phase. Thus the gallium atoms are unable to produce the chemical reaction with an adequate amount phosphorus atoms during growing GaP window layer. Moreover, there is an excess of trimethyl-gallium to form gallium atoms in the gas phase and directly to form the droplets on the surface of the GaP window layer. Those gallium atoms will absorb phosphorus atoms again; meanwhile, they become groups of nucleation. With continuously process of deposition,they turn into clusters consequently. This could be a reason to cause the present surface defects. With increasing the GaP deposition temperature to 700°C, the surface defects diminished apparently and those defects were widely distributed all over epi-wafer for about 5~10%. However, the luminous intensity of the AlGaInP LED seems to degrade from 90 to 80 mcd at an injection current of 20 mA, corresponding to an operation voltage from original 1.93 V to 2.03 V. We assumed that the higher growing temperature of GaP window layer could change Mg doping concentration. Future study is still on the way and we expect that the surface condition can be improved so as to maintain its luminance and operation voltage。
其他識別: U0005-2807200610291000
Appears in Collections:精密工程研究所

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