摘要(英) |
Improving non-uniform current spreading to obtain high light-output efficiency is one of most important topics of GaN-based light emitting diodes (LEDs). Moreover, in conventional design of LEDs, light generated under the opaque p-pad metal contact is absorbed or reflected back by the contact and re-absorbed by material. It will reduce the efficiency of light-output.
The main purpose of this thesis is to investigate three different current blocking layer (CBL) fabrication processes, including deposition of SiO2, Inductively Coupled Plasma (ICP) etching and ion implant to increase the brightness of LEDs.
For qualification the change of these three surface treatments, tested samples with transmission-line model pattern have been applied to acquire the readings of series resistance. The highest resistance readings are 3.83×106Ω, 6.62×105Ω and 8.36×107Ω for SiO2, ICP and ion implant, respectively. Achievements of LED component using CBL structure, we observe the light output power of three kinds of methods are enhanced by 3.7~9.1%, 3.2~7.1% and 5.9~7.2%, respectively. But in electricity property, each process will make forward voltage a slightly higher 0.03~0.09V, 0.03~0.07V and 0.03~0.09V due to decrease of contact surface of p-GaN.
Finally, relation between readings of series resistance and improved light output LEDs with CBL structure has been discussed by these evidences and possible mechanism has been induced in the thesis. |
參考文獻 |
[1]H. Kim, J.-M. Lee and C. Huh et al. "Modeling of a GaN-based light-emitting diode for uniform current spreading", Appl. Phys. Lett. 77, pp. 1903-1904, 2000
[2] S. Nakamura and G. Fasol, The Blue Laser Diode, Springer, New York,1997.
[3] S. Nakamura, T. Mukai and M. Senoh et al. "Thermal annealing effects on p-type Mg-doped GaN films," Jpn. J. Appl. Phys., vol.31, pp.L139-L142, 1992.
[4] S. Nakamura et al. Journal of Applied Physics 76(12), 8189 (1994).
[5] S. Nakamura, M. Senoh and N. Iwasa et al.“Superbright Green InGaN Single-Quantum-Well-Structure Light-Emitting Diodes,” Jpn. J. Appl. Phys.vol.34, pp.L1332-L1335, 1995.
[6] T. Mukai, K. Takekawa, and S. Nakamura, Jpn. J. Appl. Phys. 37, L839 (1998).
[7] S. Nakamura, M. Senoh and S. Nagahama et al. Appl. Phys. Lett. 72, 211 (1998).
[8] Chul Huh, Ji-Myon Lee and Dong-Joon Kim et al. Proceedings of SPIE Vol. 4445 (2001)
[9] Chul Huh, Ji-Myon Lee and Dong-Joon Kim et al. Journal of Applied Physics, vol.92, 2248 (2002).
[10] X. Guo and E. F. Schubert, “Current crowding in GaN/InGaN light emitting diodes on insulating substrates”, Journal of Applied Physics Vol. 90, 8 (2001)
[11] X. Guo and E. F. Schubert, “Current crowding and optical saturation effects in GaN/InGaN light-emitting diodes grown on insulating substrates”, Applied Physics Letter, Vol. 78, 3337 (2001)
[12] W. B. Joyce and S. H. Wemple, “Steady-State Junction-Current Distributions in Thin Resistive Films on Semiconductor Junctions”, Journal of Applied Physics Vol. 41, 9, 3818-3830 (1970)
[13]莊達人, VLSI製造技術, 高立圖書, (2000)
[14]I. Schnitzer, E. Yablonovitch and C. Caneau et al. "30 % external quantum efficiency from surface textured, thin-film light-emitting diodes", Appl. Phys. Lett. 63, pp. 2174-2 176, 1993
[15] Ho Won Jang and Jong-Lam Lee, “Effect of Cl2 Plasma Treatment on Metal Contacts to n-Type and p-Type GaN”, Journal of The Electrochemical Society, 150 G513-G519 (2003)
[16] H. W. Jang, C. M. Jeon and J. K. Kim et al. Appl. Phys. Lett., 78, 2015, (2001)
[17] S. M. SZE, VLSI Technology, McGraw-HILL, (1988)
[18] 敦俊儒,「離子佈植摻雜氮化鎵薄膜的光、電、結構特性之分析」,國立中央大學,碩士論文,民國90年
[19] 鍾易亨,「磷化鋁鎵銦發光二極體外部量子效率的改善」,國立成功大學,碩士論文,民國92年
[20] 呂育聰,「利用電流阻隔層及鈍化層的研究來改善氮化鎵藍光二極體的發光效率」,國立成功大學,博士論文,民國92年
[21] 劉建志,「高亮度發光二極體之設計與製作」,國立成功大學,博士論文,民國93年 |