Title: Near-field optical microscopy and scanning Kelvin microscopy studies of V-defects on AlGaN/GaN films
Authors: Ku, CS
Peng, JM
Ke, WC
Huang, HY
Tang, NE
Chen, WK
Chen, WH
Lee, MC
電子物理學系
Department of Electrophysics
Issue Date: 4-Oct-2004
Abstract: AlxGa1-xN thin film was grown on undoped GaN/sapphire (0001) substrate by metalorganic chemical vapor deposition. V-defects were directly observed by atomic force microscopy (AFM) with various size of 0.5-2 mum in diameter. In a previous study, the microphotoluminescence spectra showed an extra peak (I-v=350 nm) inside the V-defect besides the near-band-edge emission (I-nbe=335 nm). To achieve better spatial resolution, we used near-field scanning optical microscopy (NSOM) and scanning Kelvin-force microscopy (SKM) to probe the V-defect in detail. The NSOM spectra showed that the intensity of the I-v band increased gradually from V-defect edges to its center, while I-nbe remained unchanged. Besides, the SKM measurements revealed that the Fermi level decreased from the flat region to V-defect center by about 0.2 eV. These results suggest that the I-v band could be related to shallow acceptor levels, likely resulting from V-Ga defects. (C) 2004 American Institute of Physics.
URI: http://dx.doi.org/10.1063/1.1799248
http://hdl.handle.net/11536/26317
ISSN: 0003-6951
DOI: 10.1063/1.1799248
Journal: APPLIED PHYSICS LETTERS
Volume: 85
Issue: 14
Begin Page: 2818
End Page: 2820
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