Morphology of InN nanorods using spectroscopic Raman imaging

Abstract

We report the vibrational properties of vertical and oblique InN nanorods (NRs) grown by molecular beam epitaxy (MBE). Surface optical (SO) Raman mode at 561 cm−1, belonging to E1 symmetry [SO(E1)], is identified along with symmetry allowed Raman modes of E2(low), E2(high), and E1(LO) at 87, 489, and 589 cm−1, respectively, corresponding to wurtzite InN phase. Usually, SO phonon modes arise due to breakdown of translational symmetry of surface potential at surface defects, which are attributed by the surface roughness. Intensity distribution of E1(LO) and SO(E1) phonon modes over a specified area have been analysed using Raman area mapping with an optical resolution of 400 nm. Imaging with E1(LO) phonon mode, originating from the bulk of the sample, distinguishes the vertical NRs alone. We are able to resolve NR morphologies in both vertical and oblique cases with additional Raman mapping analysis of SO(E1) phonon mode, emerging from the surface irregularities, which are confined to the tip of MBE grown NRs. Copyright © 2013 John Wiley & Sons, Ltd.

Tribological behavior of hydrogenated DLC film: Chemical and physical transformations at nano-scale

“…In the post analysis, intensity of a peak is mapped to get 2D distribution corresponding to the peak. In present case, mapping is carried out for a total area of 150 m 2 , with spatial step size of 0.5 m [21]. In addition I D /I G ratio for each point was obtained from the Raman spectra and the variation is mapped across the wear track as shown in Fig.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part VIII

“…They were able to resolve NR morphologies in both vertical and oblique cases with additional Raman mapping analysis of the SO(E1) phonon mode, emerging from the surface irregularities, which are confined to the tip of MBE grown NRs. [126] Mbah and coworkers reported a rapid technique for synthesis of metallic NPs for SERS. The developed SERS substrates have significant potential in detecting nitroaromatic based-explosive materials, such as 2,4,6-trinitrotoluene molecules.…”

“…used Raman imaging to study the morphology of InN NRs. They were able to resolve NR morphologies in both vertical and oblique cases with additional Raman mapping analysis of the SO(E1) phonon mode, emerging from the surface irregularities, which are confined to the tip of MBE grown NRs . Mbah and coworkers reported a rapid technique for synthesis of metallic NPs for SERS.…”

Interface phonon modes in the [AlN/GaN]20 and [Al0.35Ga0.65N/Al0.55Ga0.45N]20 2D multi-quantum well structures

“…The frequency of such lattice vibrations are observed in between the transverse and longitudinal optical ((TO) q=0 and (LO) q=0 ) phonon modes named as IF or surface optical (SO) phonon modes. [12][13][14] The effect of surface-modulation-assisted electron-SO phonon scattering is suggested to be responsible for the prominent appearance of SO phonon modes and hence it is also known as Fröhlich modes. [11][12][13][14][15][16][17][18][19][20][21][22] The SO, as well as IF phonon modes are the vibrations of surface atoms whose amplitudes are confined near to the surface region of the materials.…”

“…26 It was well established that the SO phonon mode frequency depends on the dielectric constant of the surrounding medium ( m ), as well as the shape, interfaces, saw tooth edges, periodicity of surface defects, diameter modulation and variation of density of the nanostructures. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] In the present study, we investigated the behavior of IF phonon modes in the Raman spectra of were carried out with the help of plasma assisted molecular beam epitaxy (PAMBE). A VEECO Gen 930 system with standard effusion cells for group III sources and an RF plasma source for N activation was employed.…”