Size-independent low-frequency Raman scattering in Ge-nanocrystal-embedded SiO_2 films

Liu, L. Z.; Wu, X. L.; Gao, Fan; Yang, Yimin; Li, T. H.; Chu, Paul K.

doi:10.1364/ol.35.001022

Cited by 9 publications

(3 citation statements)

References 26 publications

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“…The superlattice annealed for 25 min with a of 45.5% has been chosen for the thickness calculation, because the nanocrystal growth process was completed in this sample. The derived thickness of surface layer is about 6.6Å which is equivalent to a few atomic layer thicknesses and agrees well with previously reported results [29][30][31][32][33]. It should be aware that a thickness of this order of magnitude is very difficult to be detected by the TEM measurement, which explains why this surface layer is not observed in Figure 1.…”

Section: Resultssupporting

confidence: 91%

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Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

Zhang

Xiang

Shrestha

et al. 2014

Journal of Nanomaterials

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Ge nanocrystals (Ge-ncs) embedded in a SiO2superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge-O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen-deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx) was then proposed to explain these findings and supplement the existing growth models for Ge-ncs in SiO2films. Further analysis of the bonding structure of Ge atoms suggested that Ge-ncs are likely to have a core-shell structure with an amorphous-like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.

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Section: Resultssupporting

confidence: 91%

“…During the fit procedure, the peak positions are limited to specific ranges, while other parameters are unbounded. some circumstances Ge-ncs have a core-shell structure with crystalline core and amorphous shell [29][30][31]. In our oxygen rich environment, the surface atoms of Ge-ncs tend to be terminated by oxygen atoms.…”

Section: Resultsmentioning

confidence: 99%

Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

Zhang

Xiang

Shrestha

et al. 2014

Journal of Nanomaterials

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“…The materials were characterized by transmission electron microscopy ͑TEM͒, Raman spectroscopy, PL, PL excitation ͑PLE͒, and x-ray diffraction ͑XRD͒ and the analytical details can be found elsewhere. 14,15 All the measurements were conducted at room temperature.…”

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confidence: 99%

Photoluminescence from colloids containing aluminum hydroxide nanocrystals with uniform size

Liu

et al. 2010

Applied Physics Letters

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Aluminum hydroxide nanocrystals consisting of an amorphous shell and crystalline core are fabricated by pulsed laser ablation of an aluminum target in water. The colloid consisting of nanocrystals with a uniform size exhibits a size-independent photoluminescence ͑PL͒ band at ϳ383 nm. According to the PL excitation spectra and time-resolved PL decay analysis, this PL band originates from oxygen vacancies in the amorphous shell and Förster energy transfer occurs between the oxygen vacancy levels in the crystalline core and amorphous shell. These phenomena are found to alter the PL excitation spectra.

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Size‐dependent evolution of phonon confinement in colloidal Si nanoparticles

Zhang

Feng

Anthony

et al. 2015

J Raman Spectroscopy

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A size‐dependent evolution of phonon confinement is revealed in Si nanoparticles (NPs) via Raman spectroscopy. By introducing a variable confinement factor, α, into a well‐known phenomenological phonon confinement model (PCM) developed by Richter et al., acceptable fits are achieved to downshifted and asymmetrically broadened Raman spectra of Si NPs with different diameters, d, from 2.4 nm to 6.3 nm. A comparative study using Raman spectra of colloidal Si NPs, for the first time, shows an apparent positive linear correlation between α and the Si NP size. Based on the PCM, the amplitude of the atomic vibration (phonon) at the real physical boundary of NPs is proportional to e−α/2, which indicates that the amplitude of the first order optical phonon is relatively larger at the edges for smaller Si nanostructures despite of their stronger phonon confinement weighed by α/d2. Copyright © 2015 John Wiley & Sons, Ltd.

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Size-independent low-frequency Raman scattering in Ge-nanocrystal-embedded SiO_2 films

Cited by 9 publications

References 26 publications

Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

Photoluminescence from colloids containing aluminum hydroxide nanocrystals with uniform size

Size‐dependent evolution of phonon confinement in colloidal Si nanoparticles

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