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ISSN : 1225-0562(Print)
ISSN : 2287-7258(Online)
Korean Journal of Materials Research Vol.24 No.12 pp.645-651
DOI : https://doi.org/10.3740/MRSK.2014.24.12.645

GaN Film Growth Characteristics Comparison in according to the Type of Buffer Layers on PSS

Chang-min Lee, Byung Hoon Kang, Dae-Sik Kim, Dongjin Byun
Department of Materials Science & Engineering, Korea University, Seoul 136-713, Korea
Corresponding author
E-Mail : dbyun@korea.ac.kr(D. Byun, Korea Univ.)
2014년 9월 16일 2014년 10월 17일 2014년 10월 22일

Abstract

GaN is most commonly used to make LED elements. But, due to differences of the thermal expansion coefficient and lattice mismatch with sapphire, dislocations have occurred at about 109~1010/cm2. Generally, a low temperature GaN buffer layer is used between the GaN layer and the sapphire substrate in order to reduce the dislocation density and improve the characteristics of the thin film, and thus to increase the efficiency of the LED. Further, patterned sapphire substrate (PSS) are applied to improve the light extraction efficiency. In this experiment, using an AlN buffer layer on PSS in place of the GaN buffer layer that is used mainly to improve the properties of the GaN film, light extraction efficiency and overall properties of the thin film are improved at the same time. The AlN buffer layer was deposited by using a sputter and the AlN buffer layer thickness was determined to be 25 nm through XRD analysis after growing the GaN film at 1070 oC on the AlN buffer CPSS (C-plane Patterned Sapphire Substrate, AlN buffer 25 nm, 100 nm, 200 nm, 300 nm). The GaN film layer formed by applying a 2 step epitaxial lateral overgrowth (ELOG) process, and by changing temperatures (1020~1070 oC) and pressures (85~300 Torr). To confirm the surface morphology, we used SEM, AFM, and optical microscopy. To analyze the properties (dislocation density and crystallinity) of a thin film, we used HR-XRD and Cathodoluminescence.

PSS 상 버퍼층 종류에 따른 GaN 박막 성장 특성 비교

이창민, 강병훈, 김대식, 변동진
고려대학교 신소재공학과

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