Defect Reduction in Semi-Polar (11\bar{2}2) Gallium Nitride Grown Using Epitaxial Lateral Overgrowth
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概要
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We report on the characterization of semi-polar (11\bar{2}2) gallium nitride (GaN) films grown on m-plane (1\bar{1}00) sapphire by an asymmetric epitaxial lateral overgrowth (ELOG) process first reported by de Mierry et al. [Appl. Phys. Lett. 94 (2009) 191903]. The overgrowth conditions were engineered to greatly enhance the growth rate along the [0001] direction, which combined with the inclination of the [0001] axis from the film surface at {\sim}32°, allowing a low defect density wing to overgrow the highly defective window region and thus eliminating basal plane stacking faults (BSFs). By correlating cross-sectional transmission electron microscopy and cathodoluminescence data, we confirm that BSFs and dislocations are terminated by the coalescence boundary formed as a result of the overgrowth anisotropy. Low temperature photoluminescence spectra reveal a strong GaN emission at 3.485 eV associated with donor-bound exciton recombination and very small BSF-related emission at 3.425 eV. The intensity ratio between the GaN bound exciton and the BSF emission is {\sim}220, which is four orders of magnitude greater than that of the semi-polar seed layer. Scanning capacitance microscopy data showed that almost the entire film is unintentionally n-type. The impurity incorporation rate is strongly dependent on which crystallographic planes are present during different stages of the ELOG process.
- 2013-08-25
著者
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Kappers Menno
Department Of Materials Science And Metallurgy University Of Cambridge
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Moram Michelle
Department Of Materials Science And Metallurgy University Of Cambridge
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Zhu Tongtong
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, U.K.
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Oliver Rachel
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, U.K.
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Badcock Tom
School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL, U.K.
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Dawson Philip
School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL, U.K.
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Sutherland Danny
School of Physics and Astronomy, Photon Science Institute, University of Manchester, Manchester M13 9PL, U.K.
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Hao Rui
Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ, U.K.
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