Micro-Raman investigations of InN-GaN core-shell nanowires on Si (111) substrate

Journal Article · Sat Jun 15 00:00:00 EDT 2013 · AIP Advances

DOI:https://doi.org/10.1063/1.4811365· OSTI ID:22118633

Sangeetha, P.; Ramakrishnan, V. ^[1]; Jeganathan, K. ^[2]

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1. Department of Laser Studies, School of Physics, Madurai Kamaraj University, Madurai-625 021 (India)
2. Centre for Nanoscience and Nanotechnology, School of Physics, Bharathidasan University, Tiruchirappalli-620 024 (India)

The electron-phonon interactions in InN-GaN core-shell nanowires grown by plasma assisted- molecular beam epitaxy (MBE) on Si (111) substrate have been analysed using micro-Raman spectroscopic technique with the excitation wavelength of 633, 488 and 325 nm. The Raman scattering at 633 nm reveals the characteristic E{sub 2} (high) and A{sub 1} (LO) phonon mode of InN core at 490 and 590 cm{sup -1} respectively and E{sub 2} (high) phonon mode of GaN shell at 573 cm{sup -1}. The free carrier concentration of InN core is found to be low in the order {approx} 10{sup 16} cm{sup -3} due to the screening of charge carriers by thin GaN shell. Diameter of InN core evaluated using the spatial correlation model is consistent with the transmission electron microscopic measurement of {approx}15 nm. The phonon-life time of core-shell nanowire structure is estimated to be {approx}0.4 ps. The micro-Raman mapping and its corresponding localised spectra for 325 nm excitation exhibit intense E{sub 2} (high) phonon mode of GaN shell at 573 cm{sup -1} as the decrease of laser interaction length and the signal intensity is quenched at the voids due to high spacing of NWs.

• OSTI ID: 22118633
• Journal Information: AIP Advances, Journal Name: AIP Advances Journal Issue: 6 Vol. 3; ISSN AAIDBI; ISSN 2158-3226
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
77 NANOSCIENCE AND NANOTECHNOLOGY
CARRIER DENSITY
CHARGE CARRIERS
ELECTRON-PHONON COUPLING
ELECTRONS
EXCITATION
GALLIUM NITRIDES
INDIUM NITRIDES
INTERACTIONS
LAYERS
MOLECULAR BEAM EPITAXY
PHONONS
PLASMA
QUANTUM WIRES
RAMAN EFFECT
SEMICONDUCTOR MATERIALS
SHELLS
SUBSTRATES
TRANSMISSION ELECTRON MICROSCOPY