Plasmon induced enhancement of surface optical phonon modes and magnon properties of NiO nanoparticles: Raman spectral probe

2020 ◽  
Vol 22 (39) ◽  
pp. 22815-22822 ◽  
Author(s):  
Anoop Sunny ◽  
Karthikeyan Balasubramanian
Keyword(s):  
Raman Spectroscopy ◽  
Optical Phonon ◽  
Room Temperature ◽  
Nio Nanoparticles ◽  
Phonon Modes ◽  
Surface Optical ◽  
Raman Spectral

In the present work, the influence of Ag-induced plasmons on the surface optical (SO) phonon modes of NiO nanoparticles was extensively studied using room temperature Raman spectroscopy.

A Raman spectral probe on polar w-ZnS nanostructures and surface optical phonon modes in nanowires

Nanoscale ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 4948-4958 ◽  
Author(s):  
Neena Prasad ◽  
Balasubramanian Karthikeyan
Keyword(s):  
Hydrothermal Method ◽  
Optical Phonon ◽  
Phonon Modes ◽  
Surface Optical ◽  
Raman Spectral

In the present study, different morphologies of ZnS nanostructures have been synthesized through a hydrothermal method and their Raman spectral modes are investigated.

Nondestructive Characterizations of Au-Catalyzed GaAs Nanowires on GaAs(111)B Substrates via Identifications of 1st Order Optical Phonon Modes Using μ-Raman Spectroscopy

2020 ◽  
Vol 20 (7) ◽  
pp. 4358-4363
Author(s):  
Jeung Hun Park ◽  
Richard S. Kim ◽  
Se-Jeong Park ◽  
Gye-Choon Park ◽  
Choong-Heui Chung
Keyword(s):  
Raman Spectroscopy ◽  
Dose Rate ◽  
Raman Spectra ◽  
Optical Phonon ◽  
Longitudinal Optical ◽  
Transverse Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Gaas Nanowires ◽  
Beam Dose

We report the relation between the catalyst patterning conditions and the intensity of the 1st order Raman active modes in Au-catalyzed GaAs nanowire bundles. We fabricated e-beam lithographically Au-patterned GaAs(111)B substrates by varying the patterning conditions (e-beam dose rate, dot-size and interdot-spacings), and grew GaAs nanowires via vapor–liquid–solid process using a solid-source molecular beam epitaxy. To understand the effects of the substrate preparation conditions and resulting morphologies on the optical characteristics of 1st order transverse optical and longitudinal optical phonon modes of GaAs, we characterized the nanowire bundles using complementary μ-Raman spectroscopy and scanning electron microscopy as a function of the e-beam dose rate (145–595 μC/cm2), inter-dot spacing (100 and 150 nm) and pattern size (100 and 150 nm). Ensembles of single crystalline GaAs nanowires covered with different Au-thickness exhibit a downshift and asymmetric broadening of the 1st order transverse optical and longitudinal optical phonon peaks relative to GaAs bulk modes. We also showed that the sensitivity of a downshift and broadening of Raman spectra are directly related to morphological and surface coverage variations in as-grown nanowires. We observed clear increases of the transverse optical and longitudinal optical intensity as well as the relatively higher peak shift and broadening of Raman spectra from the 100 nm patterning in response to the dose rate change. Strong dependence of Raman spectra of the nanowire bundles on the e-beam dose rate changes are attributed to the variations in spatial density, size, shape and random growth orientation of the wires. We have shown that the identification of the changes in GaAs longitudinal optical and Arsenic anti-site peaks is good indicators to characterize the quality of as-grown GaAs nanowires. Our finding confirms the utilization of Raman spectroscopy as a powerful tool for characterizing chemical, structural, and morphological information of as-grown nanowires within the supporting substrate.

Micro-Raman investigation on the size effects of surface optical phonon modes in single cone-shape InGaN/GaN microrods

2020 ◽  
Vol 512 ◽  
pp. 145656
Author(s):  
Hui Liao ◽  
Peijun Wen ◽  
Guo Yu ◽  
Muhammad Saddique Akbar ◽  
Junchao Li ◽  
...  
Keyword(s):  
Optical Phonon ◽  
Size Effects ◽  
Phonon Modes ◽  
Surface Optical ◽  
Single Cone

Effects of Density and Diameter on Surface Optical Phonon Modes in GaAs Nanowire Bundles

2020 ◽  
Vol 20 (7) ◽  
pp. 4444-4449
Author(s):  
Jeung Hun Park ◽  
Richard S. Kim ◽  
Se-Jeong Park ◽  
Choong-Heui Chung
Keyword(s):  
Optical Phonon ◽  
Fill Factor ◽  
Average Diameter ◽  
Red Shift ◽  
Phonon Modes ◽  
Optical Phonon Mode ◽  
Surface Optical ◽  
Gaas Nanowire ◽  
Dielectric Continuum ◽  
Dielectric Continuum Model

We report the systematic investigation of the surface optical phonon modes in Au-catalyzed GaAs nanowires grown on an Au pre-patterned GaAs(111)B substrate using μ-Raman spectroscopy. We employed electron-beam dose rate as a control parameter during the substrate patterning step for adjusting the nanowire base diameter and coverage, which are independent from the nanowire growth conditions. We have experimentally studied the effect of the fill factor and average diameter on the surface optical phonon modes and explained the red-shift and broadening of the surface optical phonon frequencies by employing the dielectric continuum model. The surface optical phonon mode shift is exhibited to be sensitive to fill factor, rather than base diameter. The decrease in the average diameter from 280 nm to 180 nm results in the asymmetric broadening and red-shift of the surface optical phonon frequency (~1.83 cm−1) but the theoretical calculation from the isolated single nanowire-based dielectric continuum model cannot solely explain the behaviors of the surface optical phonon mode. In contrast, the change in the fill factor from 0.01 to 0.83 results in a shift of the surface optical phonon frequency (~6.5 cm−1) from the GaAs bulk value. The red-shift and asymmetric broadening of the surface optical phonons, in an agreement with the Maxwell-Garnett approximation, are consequences of dipolar interaction of randomly aligned neighboring nanowires and the polar nature of GaAs nanowire bundles. This work suggests the pre-patterning parameter dependent surface optical phonon characteristics of GaAs nanowire bundles which are of great importance in the nondestructive characterization of low-dimensional opto-electronic materials and devices.

Charge-Sensitive Surface Optical Phonon in CdS Quantum Dots Studied by Resonant Raman Spectroscopy

2014 ◽  
Vol 118 (51) ◽  
pp. 30269-30273 ◽  
Author(s):  
Yongkuan Wu ◽  
Shaoqing Jin ◽  
Yun Ye ◽  
Shengyang Wang ◽  
Zhaochi Feng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Raman Spectroscopy ◽  
Optical Phonon ◽  
Cds Quantum Dots ◽  
Surface Optical ◽  
Resonant Raman

Polarization eigenvectors of surface-optical phonon modes in a rectangular quantum wire

1990 ◽  
Vol 42 (2) ◽  
pp. 1488-1491 ◽  
Author(s):  
Michael A. Stroscio ◽  
K. W. Kim ◽  
Michael A. Littlejohn ◽  
Hsuhung Chuang
Keyword(s):  
Optical Phonon ◽  
Quantum Wire ◽  
Phonon Modes ◽  
Surface Optical

Raman spectroscopy studies on the thermal stability of TiN, CrN, TiAlN coatings and nanolayered TiN/CrN, TiAlN/CrN multilayer coatings

2004 ◽  
Vol 19 (11) ◽  
pp. 3196-3205 ◽  
Author(s):  
Harish C. Barshilia ◽  
K.S. Rajam
Keyword(s):  
Thermal Stability ◽  
Raman Spectroscopy ◽  
Optical Phonon ◽  
Structural Changes ◽  
Single Layer ◽  
Multilayer Coatings ◽  
Phonon Modes ◽  
Optical Phonon Mode ◽  
Spectral Changes ◽  
Thermal Stability Of

About 1.5-μm-thick single-layer TiN, CrN, TiAlN coatings and nanolayered TiN/CrN, TiAlN/CrN multilayer coatings were deposited on silicon (111) substrates using a reactive direct current magnetron sputtering process. Structural characterization of the coatings was done using x-ray diffraction (XRD) and micro-Raman spectroscopy. All the coatings exhibited NaCl B1 structure in the XRD data. Raman spectroscopy data of as-deposited coatings exhibited two broad bands centered at 230–250 and 540–630 cm-1. These bands have been assigned to acoustical and optical phonon modes, respectively. Thermal stability of the coatings was studied by heating the coatings in air in a resistive furnace for 30 min in the temperature range 400–900 °C. Structural changes as a result of heating were characterized using Raman spectroscopy and XRD. Raman data showed that TiN, CrN, TiN/CrN, TiAlN, and TiAlN/CrN coatings started to oxidize at 500, 600, 750, 800, and 900 °C, respectively. To isolate the oxidation-induced spectral changes as a result of heating of the coatings in air, samples were also annealed in vacuum at 800 °C under similar conditions. The Raman data of vacuum-annealed coatings showed no phase transformation, and intensity of the optical phonon mode increased and shifted to lower frequencies. The origin of these spectral changes is discussed in terms of defect structure of the coatings. Our results indicate that the thermal stability of nanolayered multilayer coatings is superior to the single-layer coatings.

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