화학공학소재연구정보센터
Korean Journal of Materials Research, Vol.15, No.10, 626-631, October, 2005
Patterned substrate을 이용하여 MOCVD법으로 성장된 고효율 질화물 반도체의 광특성 및 구조 분석
Investigation of Structural and Optical Properties of III-Nitride LED grown on Patterned Substrate by MOCVD
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GaN-related compound semiconductors were grown on the corrugated interface substrate using a metalorganic chemical vapor deposition system to increase the optical power of white LEDs. The patterning of substrate for enhancing the extraction efficiency was processed using an inductively coupled plasma reactive ion etching system and the surface morphology of the etched sapphire wafer and that of the non-etched surface were investigated using an atomic force microscope. The structural and optical properties of GaN grown on the corrugated interface substrate were characterized by a high-resolution x-ray diffraction, transmission electron microscopy, atomic force microscope and photoluminescence. The roughness of the etched sapphire wafer was higher than that of the non-etched one. The surface of III-nitride films grown on the hemispherically patterned wafer showed the nano-sized pin-holes that were not grown partially. In this case, the leakage current of the LED chip at the reverse bias was abruptly increased. The reason is that the hemispherically patterned region doesn't have (0001) plane that is favor for GaN growth. The lateral growth of the GaN layer grown on (0001) plane located in between the patterns was enhanced by raising the growth temperature ana lowering the reactor pressure resulting in the smooth surface over the patterned region. The crystal quality of GaN on the patterned substrate was also similar with that of GaN on the conventional substrate and no defect was detected in the interface. The optical power of the LED on the patterned substrate was 14% higher than that on the conventional substrate due to the increased extraction efficiency.
  1. Scholz F, Harle V, Bolay H, Steuber F, Kaufmann B, Reyher G, Dornen A, Gfrorer O, Im SJ, Hangleiter A, Solid-State Electron., 41, 141 (1997)
  2. Orita K, Tamura S, Takizawa T, Ueda T, Yuri M, Takigawa S, Ueda D, Jpn. J. Appl. Phys., 43, 5809 (2004)
  3. Kawakami Y, Narukawa Y, Omae K, Fujita SG, Nakamura S, Phys. Status Solidi A, 178, 331 (2000)
  4. Zheng R, Taguchi T, Proc. of SPIE, 4996, 105 (2003)
  5. Fujii T, Gao Y, Sharma R, Hu EL, DenBaars SP, Nakamura S, Appl. Phys. Lett., 84, 855 (2004)
  6. Huh C, Lee K, Kang E, Park S, J. Appl. Phys., 93, 9383 (2003)
  7. Chang SJ, Chang CS, Su YK, Chuang RW, Lai WC, Kuo CH, Hsu YP, Lin YC, Shei SC, Lo HM, Ke JC, Sheu JK, IEEE Photon. Technol. Lett., 16, 1002 (2004)
  8. Shakya J, Kim KH, Lin JY, Jiang HX, Appl. Phys. Lett., 85, 142 (2004)
  9. Wierer JJ, Krames MR, Epler JE, Gardner NF, Craford MG, Wendt JR, Simmons JA, Sigalas MM, Appl. Phys. Lett., 84, 3885 (2004)
  10. Kim S, Oh J, Kang J, Kim D, Won J, Kim JW, Cho HK, J. Cryst. Growth, 262(1-4), 7 (2004)
  11. Han J, Ng TB, Biefeld RM, Crawford MH, Follstaedt DM, Appl. Phys. Lett, 71, 3114 (1997)
  12. Beaumont B, Vennegus P, Gibart P, Phys. Stat. Sol. B, 227, 1 (2001)
  13. Wu XH, Kapolnek D, Tarsa EJ, Heying B, Keller S, Keller BP, Mishra UK, DenBaars SP, Speck JS, Appl. Phys. Lett., 68, 1371 (1996)
  14. Li Q, Kim IW, Barnett SA, Marks LD, J. Mater. Res., 17, 1224 (2002)
  15. Bai J, Wang T, Sakai S, J. Appl. Phys., 88, 4729 (2000)
  16. Niki I, Narukawa Y, Morita D, Sonobe S, Mitani T, Tamaki H, Murazaki Y, Yamada M, Mukai T, Proc. of SPIE, 1587, 1 (2004)