First- and second-order Raman scattering in nanocrystalline silicon

Mishra, Puspashree; Jain, Kavita

doi:10.1103/physrevb.64.073304

Cited by 90 publications

(64 citation statements)

References 14 publications

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“…Features at 300, 640 and 950 cm -1 are roughly one to two orders of magnitudes less intense than the 520 cm -1 band, and are due to combination modes and overtones [42][43][44].…”

Section: Sensitivity/capabilities Of Raman Microscopymentioning

confidence: 89%

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

et al. 2017

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This study demonstrates that Raman microscopy is a suitable technique for future post mortem analyses of JET and ITER plasma facing components. We focus here on laboratory deposited and bombarded samples of beryllium and beryllium carbides and start to build a reference spectral databases for fusion relevant beryllium-based materials. We identified the beryllium phonon density of states, its second harmonic and E 2G and B 2G second harmonic and combination modes for defective beryllium in the spectral range 300-700 and 700-1300 cm -1 , lying close to Be-D modes of beryllium hydrides. We also identified beryllium carbide signature, Be 2 C, combining Raman microscopy and DFT calculation. We have shown that, depending on the optical constants of the material probed, in depth sensitivity at the nanometer scale can be performed using different wavelengths. This way, we demonstrate that multi-wavelength Raman microscopy is sensitive to in-depth stress caused by ion implantation (down to ≈30 nm under the surface for Be) and Be/C concentration (down to 400 nm or more under the surface for Be+C), which is a main contribution of this work. The depth resolution reached can then be adapted for studying the supersaturated surface layer found on tokamak deposits.2

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“…Features at 300, 640 and 950 cm -1 are roughly one to two orders of magnitudes less intense than the 520 cm -1 band, and are due to combination modes and overtones [42][43][44].…”

Section: Sensitivity/capabilities Of Raman Microscopymentioning

confidence: 89%

Preparing the future post-mortem analysis of beryllium-based JET and ITER samples by multi-wavelengths Raman spectroscopy on implanted Be, and co-deposited Be

et al. 2017

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“…However, the very clear polarization dependence of the phonon modes (described above) and the well defined layer periodicity (according to LEED and STM) demonstrate that disorder as an explanation of the phonon broadening can be neglected. Phonon confinement could occur if the average domain size of the epitaxial silicene is in the range of a few nm (∼7 nm for Si allotropes [40]). This would lead to a lifting of momentum conservation which disagrees again with the clear fulfilment of the Raman selection rules.…”

Section: −1mentioning

confidence: 99%

2D vibrational properties of epitaxial silicene on Ag(111)

et al. 2016

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The two-dimensional silicon allotrope, silicene, could spur the development of new and original concepts in Si-based nanotechnology. Up to now silicene can only be epitaxially synthesized on a supporting substrate such as Ag(111). Even though the structural and electronic properties of these epitaxial silicene layers have been intensively studied, very little is known about its vibrational characteristics. Here, we present a detailed study of epitaxial silicene on Ag(111) using in situ Raman spectroscopy, which is one of the most extensively employed experimental techniques to characterize 2D materials, such as graphene, transition metal dichalcogenides, and black phosphorous. The vibrational fingerprint of epitaxial silicene, in contrast to all previous interpretations, is characterized by three distinct phonon modes with A and E symmetries. Both, energies and symmetries of theses modes are confirmed by ab initio theory calculations. The temperature dependent spectral evolution of these modes demonstrates unique thermal properties of epitaxial silicene and a significant electron-phonon coupling. These results unambiguously support the purely two-dimensional character of epitaxial silicene up to about 300°C, whereupon a 2D-to-3D phase transition takes place. The detailed fingerprint of epitaxial silicene will allow us to identify it in different environments or to study its modifications.

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“…Confinement effects in nanostructures lead to modifications of the electronic, optical and vibrational properties. Unfortunately, if a firstorder Raman spectrum of nanocrystalline silicon has been studied extensively, the secondorder Raman scattering is investigated marginally [4,[9][10]. In the second-order Raman scattering process, two phonons of equal and opposite momentum participate and produce either line or broad continuous spectrum.…”

Section: Introductionmentioning

confidence: 99%