화학공학소재연구정보센터
홈 로그인 로그아웃 연락처 사이트맵
Korean Journal of Materials Research, Vol.11, No.7, 575-579, July, 2001
Export Citation
GaN 완충층 두께가 GaN 에피층의 특성에 미치는 영향
Effects of GaN Buffer Layer Thickness on Characteristics of GaN Epilayer
조용석1, 2, 고의관3, 박용주2, 김은규2, 황성민4, 임시종4, 변동진1, 2
  • 1고려대학교 재료공학과
  • 2한국과학기술연구원 반도체재료연구실
  • 3기초과학지원연구원 서울분소
  • 4LG 전자기술원 소자재료연구소
Yong Suk Cho1, 2, Eui Kwan Koh3, Young Ju Park4, Eun Kyu Kim4, Sung-Min Hwang5, Shi-Jong Leem5, and Dongjin Byun1, 2
  • 1Department of Materials Science and Engineering, Korea University, 1, Anam-Dong, 5-ka, Sungbook-Ku, Seoul 136-701, Korea
  • 2Semiconductor Materials Laboratory, Korea Institute of Science and Technology, P.O.Box 131, Cheongryang, Seoul 130-650
  • 3Seoul Branch, Korea Basic Science Institute, Seoul, 136-701, Korea
  • 4Semiconductor Materials Laboratory, Korea Institute of Science and Technology, P.O.Box 131, Cheongryang, Seoul 130-650, Korea
  • 5LG Electronics Institute of Technology, 16 Woomyeon-Dong, Seocho-Gu, Seoul, 137-724, Korea
초록
Metal organic chemical vapor deposition (MOCVB)법을 사용하여 sapphire (0001) 기판 위에 GaN 환충층을 성장하고, 그 위에 GaN 에피층을 성장하였다. GaN 완충층은 55 0 ? C 에서 약 26 nm에서 130 nm까지 각각 다른 두께로 성장하였고, GaN 에피층은 110 0 ? C 에서 약 4 μm 의 두께로 성장하였다. GaN 완충층 성장 후 atomic force microscopy (AFM)으로 표면 형상을 측정하였다. GaN 완충층의 두께가 두꺼워질수록 GaN 에피층의 표면이 매끈해지는 것을 scanning electron microscopy (SEM)으로 관찰하였다. 이것으로 GaN 에피층의 표면은 완충층의 두께와 표면 거칠기와 관계가 있다는 것을 알 수 있었다. GaN 에피층의 결정학적 특성을 double crystal X-ray diffraction (DCXRD)와 Raman spectroscopy로 측정하였다. 성장된 GaN 에퍼층의 광학적 특성을 photoluminescence (PL)로 조사한 결과 두께가 두꺼운 완충층 위에 성장된 에퍼층의 결정성이 더 좋은 반면, 내부 잔류응력은 증가하는 결과를 보였다. 이러한 사실들로부터 완충층의 두께가 두꺼워짐에 따라 내부 자유에너지가 감소하여 에피층 성장시 측면성장을 도와 표면이 매끈해지고, 결정성이 좋아졌다.
buffer layer ranging from 26 nm to 130 nm in thickness was grown at 55 0 ? C prior to the 4 μm thick GaN epitaxial deposition at 110 0 ? C . After GaN buffer layer growth, buffer layer surface was examined by atomic force microscopy (AFM). As the thickness of GaN buffer layer was increased, surface morphology of GaN epilayer was investigated by scanning electron microscopy (SEM). Double crystal X-ray diffraction (DCXRD) and Raman spectroscopy were employed to study crystallinity of GaN epilayers. Optical properties of GaN epilayers were measured by photoluminescence (PL). The epilayer grown with a thin buffer layer had rough surface, and the epilayer grown with a thick buffer layer had mirror-like surface of epilayer. Although the stress on the latter was larger than on the former, its crystallinity was much better. These results imply that the internal free energy is decreased in case of the thick buffer layer. Decrease in internal free energy promotes the lateral growth of the GaN film, which results in the smoother surface and better crystallinity.
Keywords:GaN;buffer layer;MOCVD
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