title: Dense, Regular GaAs Nanowire Arrays by Catalyst-Free Vapor Phase Epitaxy for Light Harvesting.
abstract: Density dependent growth and optical properties of periodic arrays of GaAs nanowires (NWs) by fast selective area growth MOVPE are investigated. As the period of the arrays is decreased from 500 nm down to 100 nm, a volume growth enhancement by a factor of up to four compared with the growth of a planar layer is observed. This increase is explained as resulting from increased collection of precursors on the side walls of the nanowires due to the gas flow redistribution in the space between the NWs. Normal spectral reflectance of the arrays is strongly reduced compared with a flat substrate surface in all fabricated arrays. Electromagnetic modeling reveals that this reduction is caused by antireflective action of the nanowire arrays and nanowire-diameter dependent light absorption. Irrespective of the periodicity and diameter, Raman scattering and grazing angle X-ray diffraction show signal from zinc blende and wurtzite phases, the latter originating from stacking faults as observed by high resolution transmission electron microscopy. Raman spectra contain intense surface phonons peaks, whose intensity depends strongly on the nanowire diameters as a result of potential structural changes and as well as variations of optical field distribution in the nanowires.
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Jiehong
authors: J
authors: Jin
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.|National Institute of Materials Physics , P.O. Box MG-7, Magurele, Bucharest 077125, Romania.
authors: Toma
authors: T
authors: Stoica
authors: Peter Grünberg Institute 8 (PGI 8) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Stefan
authors: S
authors: Trellenkamp
authors: Division of Solid State Physics and NanoLund, Lund University , Box 118, 22100 Lund, Sweden.
authors: Yang
authors: Y
authors: Chen
authors: Division of Solid State Physics and NanoLund, Lund University , Box 118, 22100 Lund, Sweden.
authors: Nicklas
authors: N
authors: Anttu
authors: Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Vadim
authors: V
authors: Migunov
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Rudy M S
authors: RM
authors: Kawabata
authors: Materials Science and Engineering, Nanyang Technological University , 639798 Singapore.
authors: Pio J S
authors: PJ
authors: Buenconsejo
authors: Materials Science and Engineering, Nanyang Technological University , 639798 Singapore.
authors: Yeng M
authors: YM
authors: Lam
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Fabian
authors: F
authors: Haas
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Hilde
authors: H
authors: Hardtdegen
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Detlev
authors: D
authors: Grützmacher
authors: Peter Grünberg Institute 9 (PGI 9) and JARA-Fundamentals of Future Information Technologies , Forschungszentrum Jülich, 52425 Jülich, Germany.
authors: Beata E
authors: BE
authors: Kardynał
keywords: GaAs nanowires; Raman spectroscopy; metalorganic vapor phase epitaxy; optical spectroscopy; selective area growth