Bandgap measurements and the peculiar splitting of E{sub 2}{sup H} phonon modes of In{sub x}Al{sub 1-x}N nanowires grown by plasma assisted molecular beam epitaxy

Journal Article · Thu Jul 28 04:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4959260· OSTI ID:22597790

Tangi, Malleswararao; Mishra, Pawan; Janjua, Bilal; Ng, Tien Khee; Prabaswara, Aditya; Anjum, Dalaver H.; Yang, Yang ^[1]; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; El-Desouki, Munir M. ^[2]

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1. Adavanced nanofabrication Imaging and characterization, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)
2. National Center for Nanotechnology, King Abdulaziz City for Science and Technology (KACST), Riyadh 11442-6086 (Saudi Arabia)

The dislocation free In{sub x}Al{sub 1-x}N nanowires (NWs) are grown on Si(111) by nitrogen plasma assisted molecular beam epitaxy in the temperature regime of 490 °C–610 °C yielding In composition ranges over 0.50 ≤ x ≤ 0.17. We study the optical properties of these NWs by spectroscopic ellipsometry (SE), photoluminescence, and Raman spectroscopies since they possesses minimal strain with reduced defects comparative to the planar films. The optical bandgap measurements of In{sub x}Al{sub 1-x}N NWs are demonstrated by SE where the absorption edges of the NW samples are evaluated irrespective of substrate transparency. A systematic Stoke shift of 0.04–0.27 eV with increasing x was observed when comparing the micro-photoluminescence spectra with the Tauc plot derived from SE. The micro-Raman spectra in the NWs with x = 0.5 showed two-mode behavior for A{sub 1}(LO) phonons and single mode behavior for E{sub 2}{sup H} phonons. As for x = 0.17, i.e., high Al content, we observed a peculiar E{sub 2}{sup H} phonon mode splitting. Further, we observe composition dependent frequency shifts. The 77 to 600 K micro-Raman spectroscopy measurements show that both AlN- and InN-like modes of A{sub 1}(LO) and E{sub 2}{sup H} phonons in In{sub x}Al{sub 1-x}N NWs are redshifted with increasing temperature, similar to that of the binary III group nitride semiconductors. These studies of the optical properties of the technologically important In{sub x}Al{sub 1-x}N nanowires will path the way towards lasers and light-emitting diodes in the wavelength of the ultra-violet and visible range.

• OSTI ID: 22597790
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 4 Vol. 120; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ABSORPTION
ALUMINIUM NITRIDES
DEFECTS
DISLOCATIONS
ELLIPSOMETRY
FILMS
INDIUM NITRIDES
LIGHT EMITTING DIODES
MOLECULAR BEAM EPITAXY
MOLECULAR BEAMS
NANOWIRES
OPACITY
PHONONS
PHOTOLUMINESCENCE
PLASMA
RAMAN SPECTRA
RAMAN SPECTROSCOPY
RED SHIFT
SEMICONDUCTOR MATERIALS