Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

Bostedt, Christoph

doi:10.2172/15005483

Cited by 4 publications

(8 citation statements)

References 82 publications

(300 reference statements)

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“…This finding is qualitatively similar to the findings of Batson and Heath on Si nanocrystals [15] and Bostedt, [16] who observed size-dependent changes in the Ge 3d ionization edge for films of polydisperse Ge nanocrystals (1.4 to 3.4 nm in diameter) using X-ray absorption spectroscopy (XAS). The onset of the size-dependent shift in the Ge 3d ionization edge occurs when the nanowire diameter is close to the Bohr exciton diameter for Ge (24 nm).…”

Section: Size Dependence Of the Volume Plasmon Energy In Ge Nanowiressupporting

confidence: 90%

Quantum confinement effects in germanium nanowires studied by electron energy loss spectroscopy (EELS)

Hanrath

Korgel

2004

SPIE Proceedings

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Organic monolayer-coated single-crystal germanium (Ge) nanowires ranging from 8 to 80 nm in diameter were synthesized by the gold nanocrystal-seeded supercritical-fluid-liquid-solid (SFLS) approach and studied by energy loss spectroscopy (ELS) on a scanning transmission electron microscope (STEM). Energy losses from a ~0.5 nm diameter electron probe due to scattering from volume and surface plasmons vary with respect to the probe position relative to the nanowire surface, and the volume plasmon energy increases with decreasing diameter for nanowires narrower than 24 nm. Below 24 nm, the organic monolayer-coated nanowires also exhibit size-dependent Ge 3d core ionization spectra that shift to higher energy with reduced diameter that are independent of probe position relative to the surface.

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Section: Size Dependence Of the Volume Plasmon Energy In Ge Nanowiressupporting

confidence: 90%

Quantum confinement effects in germanium nanowires studied by electron energy loss spectroscopy (EELS)

Hanrath

Korgel

2004

SPIE Proceedings

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“…The inflection point in the band edge increases in energy with decreasing diameter, along with an associated change in peak structure suggesting that the projected DOS in the conduction band is changing. This finding is qualitatively similar to the findings of Batson and Heath on Si nanocrystals 4 and of Bostedt, who observed size-dependent changes in the Ge 3d ionization edge for films of polydisperse Ge nanocrystals (1.4 to 3.4 nm in diameter) using X-ray absorption spectroscopy (XAS). The onset of the size-dependent shift in the Ge 3d ionization edge occurs at a nanowire diameter close to the Bohr exciton diameter for Ge (24 nm) (see Figure b).…”

supporting

confidence: 90%

“…The onset of the size-dependent shift in the Ge 3d ionization edge occurs at a nanowire diameter close to the Bohr exciton diameter for Ge (24 nm) (see Figure b). Notably, these shifts occur at significantly larger diameters than has been observed in XAS studies of Ge nanocrystal ensembles . This suggests that the p-like projected DOS probed here may be subject to more pronounced quantum confinement effects than the s- and d-like states probed in Bostedt's XAS study of size dependent Ge 2p ionization edges .…”

mentioning

confidence: 54%

“…Notably, these shifts occur at significantly larger diameters than has been observed in XAS studies of Ge nanocrystal ensembles. 35 This suggests that the p-like projected DOS probed here may be subject to more pronounced quantum confinement effects than the s-and d-like states probed in Bostedt's XAS study of size dependent Ge 2p ionization edges. 35 An inspection of the Ge band diagram reveals three closely spaced energy minima with the absolute minimum at the L point and other local minima within 0.05 to 0.12 eV at the X and Γ point.…”

mentioning

confidence: 69%

“…35 This suggests that the p-like projected DOS probed here may be subject to more pronounced quantum confinement effects than the s-and d-like states probed in Bostedt's XAS study of size dependent Ge 2p ionization edges. 35 An inspection of the Ge band diagram reveals three closely spaced energy minima with the absolute minimum at the L point and other local minima within 0.05 to 0.12 eV at the X and Γ point. Empirical pseudopotential calculations by Reboredo and Zunger 36 have shown that the quantum confinement effects are more pronounced at the L and Γ points than at the X point.…”

mentioning

confidence: 69%

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A Comprehensive Study of Electron Energy Losses in Ge Nanowires

Hanrath

Korgel

2004

Nano Lett.

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We present a comprehensive study of electron energy losses by fast electrons that occur in isolated single-crystal Ge nanowires with organic monolayer-passivated surfaces. A ∼0.5 nm diameter electron probe in a scanning transmission electron microscope equipped with an energy loss spectrometer (STEM-ELS) was used to study plasmon and core electron excitations. Losses due to scattering from volume and surface plasmons vary with respect to the probe position relative to the nanowire surface, and the volume plasmon energy increases with decreasing diameter for nanowires narrower than 24 nm. Below 24 nm, the organic monolayer-coated nanowires also exhibit size-dependent Ge 3d core ionization spectra that shift to higher energy with reduced diameter that are independent of probe position relative to the surface. In contrast, the Ge 3d edge for surface-oxidized nanowires exhibits a chemically induced shift when positioned near the surface.

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Evidence for cubic phase in deposited germanium nanocrystals

Bostedt

Buuren

Plitzko

et al. 2003

J. Phys.: Condens. Matter

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Germanium nanocrystals with sizes ranging from 1 to 5 nm are condensed out of the gas phase in helium or argon buffer-gas atmospheres and subsequently deposited. The generated particle sizes are found to depend on the buffer gas, with helium yielding a narrower size distribution than argon and argon exhibiting a stronger pressure dependence of the produced particle sizes. Structural analysis of nanoparticles with average sizes around 5 nm reveals the bulklike cubic (diamond) phase—in contrast to recent experiments which suggest the tetragonal phase for similar-sized particles. These results are explained in terms of particle formation dynamics.

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Electronic Structure of Germanium Nanocrystal Films Probed with Synchrotron Radiation

Cited by 4 publications

References 82 publications

Quantum confinement effects in germanium nanowires studied by electron energy loss spectroscopy (EELS)

Quantum confinement effects in germanium nanowires studied by electron energy loss spectroscopy (EELS)

A Comprehensive Study of Electron Energy Losses in Ge Nanowires

Evidence for cubic phase in deposited germanium nanocrystals

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