Polarization Raman spectroscopy of GaN nanorod bundles

• Published in: Journal of applied physics 2010-08, Vol.108 (3), p.033504-033504-6
• Main Authors: Tite, T., Lee, C. J., Chang, Y.-M.
• Format: Article
• Language: English
• Subjects: CORRELATIONS; CRYSTAL GROWTH; CRYSTAL GROWTH METHODS; CRYSTALS; ELECTRON MICROSCOPY; EPITAXY; GALLIUM COMPOUNDS; GALLIUM NITRIDES; LASER SPECTROSCOPY; MATERIALS; MATERIALS SCIENCE; MICROSCOPY; MOLECULAR BEAM EPITAXY; NANOSCIENCE AND NANOTECHNOLOGY; NANOSTRUCTURES; NITRIDES; NITROGEN COMPOUNDS; ORIENTATION; PLASMA; PNICTIDES; POLARIZATION; PROCESSING; RAMAN SPECTRA; RAMAN SPECTROSCOPY; RELAXATION; SELECTION RULES; SEMICONDUCTOR MATERIALS; SPECTRA; SPECTROSCOPY; STRAINS; TRANSMISSION ELECTRON MICROSCOPY
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.3460811

We performed polarization Raman spectroscopy on single wurtzite GaN nanorod bundles grown by plasma-assisted molecular beam epitaxy. The obtained Raman spectra were compared with those of GaN epilayer. The spectral difference between the GaN nanorod bundles and epilayer reveals the relaxation of Raman selection rules in these GaN nanorod bundles. The deviation of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules is attributed to both the orientation of the crystal axis with respect to the polarization vectors of incident and scattered light and the structural defects in the merging boundary of GaN nanorods. The presence of high defect density induced by local strain at the merging boundary was further confirmed by transmission electron microscopy. The averaged defect interspacing was estimated to be around 3 nm based on the spatial correlation model.