Predicting Raman line shapes from amorphous silicon clusters for estimating short‐range order

Rani, Chanchal; Tanwar, Manushree; Kandpal, Suchita; Ghosh, Tanushree; Pathak, Devesh K.; Chaudhary, Anjali; Kumar, Rajesh

doi:10.1002/jrs.6117

Cited by 17 publications

(15 citation statements)

References 68 publications

(101 reference statements)

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“…Line shapes of Raman spectra from NSs are expected to be intermediate between those of the corresponding crystalline and amorphous materials. For example, a broad band around 480 cm −1 is observed in the Raman spectra from amorphous Si, [ 81–83 ] whereas at the other extreme in case of c‐Si, a sharp symmetric Lorentzian peak, is observed at ~520.5 cm −1 corresponding to the zone‐centered phonon. Experimental Raman line shape originating from spherical microcrystal was theoretically modeled by Richter et al [ 71 ] by considering the relaxation of crystal momentum in the creation and decay of phonons in the microcrystal, which was later modified by Campbell and Fauchet [ 72 ] for the exact shape of microcrystal vis‐à‐vis spherical, columnar, or thin slab by assigning different order of confinement to the confinement function.…”

Section: Origin Of Asymmetric Raman Line Shape In Siliconmentioning

confidence: 99%

Effect of some physical perturbations and their interplay on Raman spectral line shapes in silicon: A brief review

Kumar

Tanwar

2021

J Raman Spectroscopy

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Raman spectroscopy is a proven versatile tool for characterization of materials spanning almost all areas of science because of its ability to non-invasively extract information about materials. This technique is able to detect any perturbation in a system that can affect the phonons. A detailed discussion on various factors that affect the Raman line shape for a material has been summarized here by taking the example of silicon. Methods to identify the actual reason(s) behind the observed Raman spectral line shape have also been briefly discussed. Raman line shape obtained from silicon nanostructures when analyzed closely along with their bulk counterparts, reveals important information about the quantum confinement in such systems characterized by the Bohr's exciton radius. Raman line-shape parameters are analyzed closely to understand the influence of any perturbation like quantum confinement, heavy doping, temperature rise, pressure, excitation wavelength, electronphonon interaction, and so on. Current review briefly deals with the origin of asymmetric Raman line shapes in (nano-) silicon due to various physical perturbations and their interplays, which becomes the origin of different line shapes. Advantages of using Raman microscopy in analyzing subtler physical processes taking place in a semiconductor have also been underlined.

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Section: Origin Of Asymmetric Raman Line Shape In Siliconmentioning

confidence: 99%

Effect of some physical perturbations and their interplay on Raman spectral line shapes in silicon: A brief review

Kumar

Tanwar

2021

J Raman Spectroscopy

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“…Later on, DMM-BPM method has been successfully used in Ref. 40 for the description and analysis of amorphous Si Raman data.…”

Section: Introductionmentioning

confidence: 99%

Effects of Bond Disorder and Surface Amorphization on Optical Phonon Lifetimes and Raman Peak Shape in Crystalline Nanoparticles

2021

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Optical phonons in nanoparticles with randomness of interatomic bonds are considered both analytically and numerically. For weak dilute disorder, two qualitatively different regimes of separated and overlapped levels are observed, resembling the case of random atomic masses investigated previously. At stronger and/or more dense disorder, the particles become essentially inhomogeneous, thus constituting a minimal model to describe an amorphous phase, where the picture of vibrational modes becomes more subtle. We concentrate here on the experimentally relevant case of a strong disorder located near the particle surface and formulate the core-shell model aimed to describe the ubiquitous phenomenon of particle surface amorphization. We observe a peculiar effect of volume optical phonons "repelling" from the disordered shell. It results in the Raman spectrum appearing in the form of a combination of narrow well-resolved peaks stemming from the quantized modes of a pure particle core (red-shifted due to its effective smaller size) and a wide pedestallike signal from the disordered shell, placed primarily to the right of the main Raman peak.

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“…While the above analysis has been concentrated on weakly disordered nanocrystals , later on, it has been extended onto the Raman spectra of amorphous silicon. [ 37 ]…”

Section: Introductionmentioning

confidence: 99%

“…While the above analysis has been concentrated on weakly disordered nanocrystals, later on, it has been extended onto the Raman spectra of amorphous silicon. [37] This paper is aimed to demonstrate the practical applicability of the theory developed in previous works [19,20,[34][35][36] as a regular powerful method of interpreting the Raman spectra of nanopowders of nonpolar crystals. The best way to do it is to reexamine existing experiments, extracting from the data precise and detailed information.…”

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confidence: 99%

Bench tests for microscopic theory of Raman scattering in powders of disordered nonpolar crystals: Nanodiamonds and beyond

Yashenkin

Utesov

Koniakhin³

2021

J Raman Spectroscopy

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Recent Raman data on nanocrystallite arrays are revised within the microscopic theory for Raman peaks positions and broadening (linewidth). The theory combines the elasticity theory-like approach for optical phonons used in order to evaluate the Raman peaks structure and the Green's function method applied for the phonon lines broadening. These theories are supported by the atomistic calculations within the dynamical matrix method for optical phonons and by the bond polarization model used to calculate the Raman intensities. The experimental data on four various nanopowders are analyzed with the use of this theory. The large width of the Raman peak in nanoparticles as compared with the corresponding peak in bulk materials and the width inverse dependence on the particle size previously observed by other researchers are explained within the framework of the theory. It is shown that the theory is capable to extract confidently from the Raman data four important microscopic characteristics of the nanopowder including the mean particle size, the variance of the particle size distribution function, the strength of intrinsic disorder in the particle, and the effective faceting number that parameterizes the particle shape.

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Predicting Raman line shapes from amorphous silicon clusters for estimating short‐range order

Cited by 17 publications

References 68 publications

Effect of some physical perturbations and their interplay on Raman spectral line shapes in silicon: A brief review

Effect of some physical perturbations and their interplay on Raman spectral line shapes in silicon: A brief review

Effects of Bond Disorder and Surface Amorphization on Optical Phonon Lifetimes and Raman Peak Shape in Crystalline Nanoparticles

Bench tests for microscopic theory of Raman scattering in powders of disordered nonpolar crystals: Nanodiamonds and beyond

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