Progress in Preparation of Patterned Sapphire Substrate for GaN-based Light Emitting Diodes

doi:10.3724/SP.J.1077.2012.11785

Abstract

Abstract: GaN-based light emitting diodes are extensively used for light emitting diodes in the green to ultraviolet (UV) wavelength region and have already been widely used in traffic signals, outdoor displays, full-color displays and back lighting in liquid-crystal displays. Although GaN-based light emitting diodes are commercially available, it is still difficult to manufacture highly efficient GaN-based light emitting diodes due to the high dislocation density and the low light extraction efficiency. Patterned sapphire substrates for GaN-based light-emitting diodes have attracted much interest in recent years because it can not only reduce the threading dislocation density of epitaxial GaN films, but also improve the light extraction efficiency of GaN-based light-emitting diodes. A comprehensive review is presented on the mechanisms responding for performance enhancement of GaN-based light emitting diodes on patterned sapphire substrates, methods of preparing patterned sapphire substrates and pattern-size of patterned sapphire substrates. What is more, improved performance of GaN-based light-emitting diodes on patterned sapphire substrates prepared by different methods and pattern-size are further discussed in detail. In view of the existing problems, the prospects for future development of patterned sapphire substrates are also proposed.

Key words: patterned sapphire substrate, GaN, LED, epitaxial lateral overgrowth, review

CLC Number:

TN304

CUI Lin, WANG Gui-Gen, ZHANG Hua-Yu, ZHOU Fu-Qiang, HAN Jie-Cai. Progress in Preparation of Patterned Sapphire Substrate for GaN-based Light Emitting Diodes[J]. Journal of Inorganic Materials, 2012, 27(9): 897-905.

References

[1] Ju Inchan, Kwon Yongwook, Shin Chan-Soo, et al. High-power GaN-based light-emitting diodes using thermally stable and highly reflective nano-scaled Ni-Ag-Ni-Au mirror. IEEE Photonics Technology Letters, 2011, 23(22): 1685–1687.

[2] Seo Tae Hoon, Lee Kang Jea, Park Ah Hyun, et al. Enhanced light output power of near UV light emitting diodes with graphene/ indium tin oxide nanodot nodes for transparent and current spreading electrode. Optics Express, 2011, 19(23): 23111–23117.

[3] Lee Yeeu-Chang, Chen Chih-Yeeu, Chou Yen-Yu, et al. Fabri-cation of high-refractive-index microstructures and their applications to the efficiency improvement of GaN-based LEDs. Optics Express, 2011, 19(23): A1231–A1236.

[4] Lee Sang-Jun, Cho Chu-Young, Hong Sang-Hyun, et al. Im-proved performance of GaN-based light-emitting diodes with high-quality GaN grown on InN islands. J. Phys. D: Appl. Phys., 2011, 44(42): 425101–1–5.

[5] Sheu J K, Tu S J, Lee M L, et al. Enhanced light output of GaN-based light-emitting diodes with embedded voids formed on Si-implanted GaN layers. IEEE Electron Device Letters, 2011, 32(10): 1400–1402.

[6] Lin Yu-Sheng, Yeh J. Andrew. GaN-based light-emitting diodes grown on nanoscale patterned sapphire substrates with void-embedded cortex-like nanostructures. Applied Physics Express, 2011, 4(9): 092103–1–3.

[7] Lee Hee-Kwan, Kim Myung-Sub, Yu Jae-Su. Light-extraction enhancement of large-area GaN-based LEDs with electrochemically grown ZnO nanorod arrays. IEEE Photonics Technology Letters, 2011, 23(17): 1204–1206.

[8] Sun Yongjian, Trieu Simeon, Yu Tongjun, et al. GaN-based LEDs with a high light extraction composite surface structure fabricated by a modified YAG laser lift-off technology and the patterned sapphire substrates. Semiconductor Science and Technology, 2011, 26(8): 085008–1–5.

[9] Kao C C, Su Y K, Lin C L. Enhancement of light output power of GaN-based light-emitting diodes by a reflective current blocking layer. IEEE Photonics Technology Letters, 2011, 23(14): 986–988.

[10] Chiu Ching-Hsueh, Tu Po-Min, Lin Chien-Chung, et al. Highly efficient and bright LEDs overgrown on GaN nanopillar substrates. IEEE Journal of Selected Topics in Quantum Electronics, 2011, 17(4): 971–978.

[11] Wang Guigen, Zuo Hongbo, Zhang Huayu, et al. Preparation, quality characterization, service performance evaluation and its modification of sappire crystal for optical window and dome application. Material and Design, 2010, 31(2): 706–711.

[12] Hsu Hsiao-Chiu, Su Yan-Kuin, Huang Shyh-Jer, et al. Effects of trimethylgallium flow rate on a-plane GaN growth on r-plane sapphire during one-sidewall-seeded epitaxial lateral overgrowth. Applied Physics Express, 2011, 4(3): 035501–1–3.

[13] Hong Kim-Eun, Chan Kim-Kyoung, Ho Kim-Dong, et al. In-GaN/ GaN white light-emitting diodes embedded with europium silicate thin film phosphor. IEEE Journal of Quantum Electronics, 2010, 46(9): 1381–1387.

[14] Huang Chen-Yang, Ku Hao-Min, Liao Chen-Zi, et al. MQWs InGaN/ GaN LED with embedded micro-mirror array in the epitaxial- lateral-overgrowth gallium nitride for light extraction enhancement. Optics Express, 2010, 18(10): 10674–10684.

[15] Oliver R A, Bennett S E, Sumner J, et al. Scanning capacitance microscopy studies of GaN grown by epitaxial layer overgrowth. Journal of Physics Conference Series, 2010, 209: 012049–1–4.

[16] Roskowski A M, Preble E A, Einfeldt S, et al. Investigations regarding the maskless pendeo-epitaxial growth of GaN ?lms prior to coalescence. IEEE J. Quantum Electron, 2002, 38(8): 1006–1016.

[17] Bishop S M, Park J S, Gu J, et al. Growth evolution and pendeo- epitaxy of non-polar AlN and GaN thin films on 4H-SiC ( ). Journal of Crystal Growth, 2007, 300(1): 83–89.

[18] Liliental-Weber Z. TEM studies of GaN layers grown in non-polar direction: Laterally overgrown and pendeo-epitaxial layers. Journal of Crystal Growth, 2008, 310(17): 4011–4015.

[19] KANG Dong-Hun, SONG Jae-Chul, SHIM Byung-Young, et al. Characteristic comparison of GaN grown on patterned sapphire substrates following growth time. Japanese Journal of Applied Physics, 2007, 46(4B): 2563–2566.

[20] Jeong Seong-Muk, Kissinger Suthan, Kim Dong-Wook, et al. Characteristic enhancement of the blue LED chip by the growth and fabrication on patterned sapphire (0001) substrate. Journal of Crystal Growth, 2010, 312(2): 258–262.

[21] Song Jae-Chul, Lee Seon-Ho, Lee In-Hwan, et al. Character-istics comparison between GaN epilayers grown on patterned and unpatterned sapphire substrate (0001). Journal of Crystal Growth, 2007, 308(2): 321–324.

[22] Wang Woei-Kai, Wuu Dong-Sing, Lin Shu-Hei, et al. Ef?ciency improvement of near-ultraviolet InGaN LEDs using patterned sapphire substrates. IEEE Journal of Quantum Electronics, 2005, 41(11): 1403–1409.

[23] Yamada M, Mitani T, Narukawa Y, et al. InGaN-based near-ultraviolet and blue-light-emitting diodes with high external quantum efficiency using a patterned sapphire substrate and a mesh electrode. Japanese Journal of Applied Physics., 2002, 41(2): L1431–L1433.

[24] Jun Park-Dong, Lee Jeong-Yong. Dislocation reduction in GaN epilayers by maskless pendeo-epitaxy process. Journal of the Korean Physical Society, 2004, 45(5): 1253–1256.

[25] Liu Hai-Ping, Chen In-Gann, Tsay Jenq-Dar, et al. Influence of growth temperature on surface morphologies of GaN crystals grown on dot-patterned substrate by hydride vapor phase epitaxy. Journal of Electroceramics, 2004, 13(1/2/3): 839–846.

[26] Kappers M J, Datta R, Oliver R A, et al. Threading dislocation reduction in (0001) GaN thin films using SiNx interlayers. Journal of Crystal Growth, 2007, 300(1): 70–74.

[27] HIRAMATSU Kazumasa, MOTOGAITO Atsushi, MIYAKE Hideto, et al. Crystalline and optical properties of ELO GaN by HVPE using tungsten mask. IEICE Trans. Electron., 2000, E83-C(4): 620–626.

[28] Nakamura. Shuji. The roles of structural imperfections in in-GaN-based blue light emitting diodes and laser diodes. Science, 1998, 281: 956–961.

[29] Gao Haiyong, Yan Fawang, Zhang Yang, et al. Fabrication and characterization of GaN-based LEDs grown on nanopatterned sapphire substrates. Phys. Stat. Sol. (a), 2008, 205(7): 1719–1723.

[30] Zhao Shuang, Wang Kai, Chen Fei, et al. Lens design of LED searchlight of high brightness and distant spot. Journal of the Optical Society of America a - Optics Image Science and Vision, 2011, 28(5): 815–820.

[31] Zhmakin, A I. Enhancement of light extraction from light emitting diodes. Physics Reports - Review Section of Physics Letters, 2011, 498(4/5): 189–241.

[32] Zheng Zhen-rong, Hao Xiang, Liu Xu. Freeform surface lens for LED uniform illumination. Applied Optics, 2009, 48(35): 6627–6634.

[33] Kim Hyunsoo, Ahn Kwang-Soon. Enhanced light extraction of GaN-based light emitting diodes fabricated with deeply etched mesa holes. Electrochemical and Solid State Letters, 2010, 13(4): H131–H133.

[34] Lee Yeeu-Chang, Ni Ching-Huai, Chen Chih-Yeeu, et al. Enhancing light extraction mechanisms of GaN-based light-emitting diodes through the integration of imprinting microstructures, patterned sapphire substrates, and surface roughness. Optics Express, 2010, 18(S4): A489–A498.

[35] Gao Haiyong, Yan Fawang, Zhang Yang, et al. Enhancement of the light output pow