Raman shifts in Si nanocrystals

Zi, Jian; Buscher, H.; Falter, Claus; Ludwig, Wolfgang; Zhang, Kaiming; Xie, Xide

doi:10.1063/1.117371

Cited by 419 publications

(269 citation statements)

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“…To obtain a good interpretation of the experimental data many other models such as the microscopic force model [4], the bond polarizable model [13][14] and the spatial correlation model [15] have been reported. But these models do not satisfactorily describe the phonon confinement and are fail in explaining the experimental data particularly the shift and linewidth of the peak simultaneously.…”

Section: Introductionmentioning

confidence: 99%

Modified phonon confinement model for size dependent Raman shift and linewidth of silicon nanocrystals

Gupta

Jha

2009

Solid State Communications

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Section: Introductionmentioning

confidence: 99%

Modified phonon confinement model for size dependent Raman shift and linewidth of silicon nanocrystals

Gupta

Jha

2009

Solid State Communications

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“…Due to the confinement effect in nanocrystals, the Brillouin zone centre optical mode, observed in the Raman spectrum of crystalline Si at ~520 cm -1 , shifts to smaller wave numbers and broadens [8]. Zi et al describe the Raman shift for Si nanocrystals (NC) by the formula [9]:…”

Section: Resultsmentioning

confidence: 99%

Some aspects of pulsed laser deposition of Si nanocrystalline films

Polyakov

Petruhins

Butikova

et al. 2009

Eur. Phys. J. Appl. Phys.

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Nanocrystalline silicon films were deposited by a picosecond laser ablation on different substrates in vacuum at room temperature. A nanocrystalline structure of the films was evidenced by atomic force microscopy (AFM), optical and Raman spectroscopies. A blue shift of the absorption edge was observed in optical absorption spectra, and a decrease of the optical phonon energy at the Brillouin zone centre was detected by Raman scattering. Early stages of nanocrystalline film formation on mica and HOPG substrates were studied by AFM. Mechanism of nanocrystal growth on substrate is discussed.

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“…1 -5 With miniaturization of a solid down to nanometer scales, the optical Raman modes shift toward lower wavenumbers. 6 On the other hand, when the temperature is increased, the Raman peaks also shift down to low wavenumbers monotonically yet nonlinearly at low temperatures. 7 -9 It is expected that the magnitude of vibration for a surface atom is always greater than that in the bulk.…”

Section: Introductionmentioning

confidence: 99%

Atomistic origin and temperature dependence of Raman optical redshift in nanostructures: a broken bond rule

Pan

Tay

et al. 2007

J Raman Spectroscopy

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Consistent insight is presented into the atomistic origin and temperature (T) dependence of the redshift of Raman optical modes in nanostructures from INTRODUCTIONThe vibration of under-coordinated atoms at a surface and in a nanosolid is of great importance because the behavior of surface phonons influences directly the electrical, optical, and dielectric properties in semiconductor materials and devices, such as electron-phonon coupling, photoabsorption, and photoemission, as well as phonon scattering in the transport dynamics of electrons, phonons, and photons in devices. 1 -5 With miniaturization of a solid down to nanometer scales, the optical Raman modes shift toward lower wavenumbers. 6 On the other hand, when the temperature is increased, the Raman peaks also shift down to low wavenumbers monotonically yet nonlinearly at low temperatures. 7 -9 It is expected that the magnitude of vibration for a surface atom is always greater than that in the bulk. 10,11 However, the underlying mechanisms behind the size-and temperatureinduced Raman redshift of the optical modes remain ambiguous.Ł Correspondence to: Chang Q. Sun, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, Singapore. E-mail: ecqsun@ntu.edu.sg Size-induced Raman redshiftThe size-induced redshift of Raman optical modes has usually been suggested to be activated by surface disorder, 12 surface stress, 13 -15 quantum confinement, 16 -19 local heating effects, 20 -22 or surface chemical passivation. The Raman shifts of TiO 2 particles are attributed to the effects of decreasing particle size on the force constants and the amplitudes of vibration of the nearest atomic neighbors. 23 However, the effect of stress can usually be ignored for hydrogenated silicon, 24,25 in which hydrogen atoms terminate the surface dangling bonds, which reduce the bond strains and hence the residual stress. The phonon quantum confinement argument 16 attributes the redshift of the asymmetric Raman line to the relaxation of the q-vector selection rule for the excitation of the Raman active phonons due to their localization. The relaxation of the momentum conservation rule arises from the finite crystalline size and the distribution of the diameters of the nanosolid in the films. When the size is decreased, the rule of momentum conservation will be relaxed and the Raman active modes will not be limited to the center of the Brillouin zone. 13 However, Alim et al. 21,22 who have measured resonant and nonresonant Raman scattering spectra for ZnO nanocrystals with an average diameter of 20 nm, proposed that the observed phonon redshift can be attributed to the local heating effects instead of phonon Atomistic origin and temperature dependence of Raman redshift in nanostructures 781 confinement effects. A Gaussian-type phonon confinement model 17 that has been used to fit the experimental data indicates that strong phonon damping is present, whereas calculations 26 using the correlation functions of the local dielectric constant...

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Raman shifts in Si nanocrystals

Cited by 419 publications

References 1 publication

Modified phonon confinement model for size dependent Raman shift and linewidth of silicon nanocrystals

Modified phonon confinement model for size dependent Raman shift and linewidth of silicon nanocrystals

Some aspects of pulsed laser deposition of Si nanocrystalline films

Atomistic origin and temperature dependence of Raman optical redshift in nanostructures: a broken bond rule

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