Changes in the Electronic Properties of Si Nanocrystals as a Function of Particle Size

Buuren, T. van; Dinh, L. N.; Chase, L. L.; Siekhaus, Wigbert J.; Terminello, Louis J.

doi:10.1103/physrevlett.80.3803

Cited by 467 publications

(386 citation statements)

References 19 publications

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“…That means due to quantum confinement, the conduction band (CB) energy increased, while valence band (VB) energy reduced. Figure 5 shows the CB edge shift determined from L-edge data as a function of the VB shift determined from photoemission, for a series of different samples [28]. Careful inspiration indicated that the confinement decreases the VB edge twice as much as it increases the CB edge, in agreement with effective mass theory [42].…”

Section: Size Effect On the Peak Position Of Plsupporting

confidence: 61%

“…The other methods to produce porous silicon-related nanostructures include reactive sputtering [17], solgel techniques [18], SiO 2 implantation [19], selfassembly [20], growth in inverse micelles [21,22], laser ablation [23], thermal annealing [24][25][26], thermal vaporization [27,28], decomposition of silanes [29][30][31][32][33], solution synthesis [34][35][36], hybrid techniques [37], and plasma processing [38][39][40].…”

Section: Other Methodsmentioning

confidence: 99%

“…Figure 6 illustrates this relationship. Since the VB shift is equal to twice the CB band shift, the bandgap of -Si samples is obtained from [28] E gap ¼ÄE vb þÄE cb þ 1:12 eV ¼ 3ÄE cb þ 1:12 eV ð2Þ…”

Section: Size Effect On the Peak Position Of Plmentioning

confidence: 99%

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Optical Properties of Nanostructured Silicon

Chao

2011

Comprehensive Nanoscience and Technology

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Section: Size Effect On the Peak Position Of Plsupporting

confidence: 61%

Section: Other Methodsmentioning

confidence: 99%

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Optical Properties of Nanostructured Silicon

Chao

2011

Comprehensive Nanoscience and Technology

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“…The lowest unoccupied electronic states stem from the hydrogen surface termination and do not shift in energy as a function of size 3 , in contrast to Si and Ge 6,7 . The highest occupied states, however, exhibit clear size-dependent shifts 5,8 , similar to other group IV nanoparticles 6,9 . This demonstrates the ability to tune HOMO-LUMO gaps and other electronic properties based on diamondoid size 10 .…”

Section: Introductionmentioning

confidence: 89%

Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

et al. 2008

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Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using nearedge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 ± 0.05 eV and 0.16 ± 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.3

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“…If the energy of the PL above the bulk silicon band gap is due to confinement of the exciton in the nanostructure, it would be expected that the emission wavelength should shift with the dimension of the nanostructure [18]. The PL intensity increase with potential energy of the ion at constant irradiance suggests that the area of each impact increases with potential energy of the ion.…”

Section: Resultsmentioning

confidence: 99%

Exciton dispersion in silicon nanostructures formed by intense, ultra-fast electronic excitation

Hamza

Newman

Thielen

et al. 2003

Applied Physics A: Materials Science & Processing

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The intense, ultra-fast electronic excitation of clean silicon (100)-(2 × 1) surfaces leads to the formation of silicon nanostructures embedded in silicon, which photoluminesce in the yellow-green (∼ 2-eV band gap). The silicon surfaces were irradiated with slow, highly charged ions (e.g. Xe 44+ and Au 53+ ) to produce the ultra-fast electronic excitation. The observation of excitonic features in the luminescence from these nanostructures has recently been reported. In this paper we report the dispersion of the excitonic features with laser excitation energy. A phonon-scattering process is proposed to explain the observed dispersion. Bulk silicon is a poor light emitter owing to its indirect band gap. Since 1990 many authors have observed visible-light emission from silicon nanostructures. Two of the prominent examples are porous silicon (e.g. [1,2]) and silicon nanoclusters in silica (e.g. [3]). Visible emission has also been observed from one-dimensionally confined silicon in silicon/SiO 2 superlattices [4]. Many authors show that the visible emission can be due to quantum confinement of the excitation to a structure with less than 5-nm radius (Bohr radius of an exciton in silicon) (e.g. [2]). Confinement leads to a widening of the band gap and increased oscillator strength for the transition (e.g. [5]). The extent of changes (direct versus indirect) in the band structure of nanostructures of silicon is still a controversial topic (e.g. [6,7]).Recently, we have briefly reported the observation of light emission from nanostructures on silicon formed by intense, ultra-fast electronic excitation [8]. The intense, ultra-fast electronic excitation of clean silicon (100)-(2 × 1) surfaces leads to the formation of silicon nanostructures embedded in silicon, which photoluminesce at ∼560-nm wavelength (∼ 2-eV band gap). The silicon surfaces were irradiated with slow, and Au 53+ ) to produce the electronic excitation. The observation of excitonic features in the luminescence is particularly unusual for silicon nanostructures. The temperature dependence of the luminescence and the measurement of the triplet-singlet splitting of the emission strongly support the excitonic assignment. Intense, ultra-fast electronic excitation of a semiconductor surface such as silicon leads to the promotion of many (> 10 3 ) valence (bonding) electrons into the conduction bands (antibonding states). The promotion of a single electron or even many electrons into antibonding states does not impart a sufficient force for a sufficient length of time to cause displacement of the atomic nuclei. In contrast, the high density of electrons in antibonding states created by an intense, ultra-fast electronic excitation can impart an impulse leading to atomic displacements [9][10][11][12]. Direct evidence of atomic motion on a ∼160-fs time scale due to antibonding state excitation is reported by Petek et al. [13].The deposition of potential energy from slow, highly charged ions (SHCI) such as Xe 44+ (616-keV kinetic energy in this study) in se...

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Changes in the Electronic Properties of Si Nanocrystals as a Function of Particle Size

Cited by 467 publications

References 19 publications

Optical Properties of Nanostructured Silicon

Optical Properties of Nanostructured Silicon

Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

Exciton dispersion in silicon nanostructures formed by intense, ultra-fast electronic excitation

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