Quantum Confined Luminescence in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Si</mml:mi><mml:mi>/</mml:mi><mml:mrow><mml:msub><mml:mrow><mml:mi>SiO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Superlattices

Lockwood, D. J.; Lu, Zhenguo; Baribeau, J.‐M.

doi:10.1103/physrevlett.76.539

Cited by 449 publications

(206 citation statements)

References 18 publications

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“…[27,28] The change in the valence band maximum (VBM) and conduction band minimum (CBM) position was measured using XPS and Si L 2,3 edge absorption spectroscopy, respectively, and room temperature PL spectroscopy was measured. 28, the change in E G was fitted with A = 0.7 and E Gap (∞)=1.6 eV, as in Eq. (3).…”

Section: Quantum Wellmentioning

confidence: 99%

Quantum confinement in Si and Ge nanostructures

Barbagiovanni

Lockwood

Simpson

et al. 2012

Journal of Applied Physics

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179

163

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We apply perturbative effective mass theory as a broadly applicable theoretical model for quantum confinement (QC) in all Si and Ge nanostructures including quantum wells (QWs), wires (Q-wires) and dots (QDs). Within the limits of strong, medium, and weak QC, valence and conduction band edge energy levels (VBM and CBM) were calculated as a function of QD diameters, QW thicknesses and Q-wire diameters. Crystalline and amorphous quantum systems were considered separately. Calculated band edge levels with strong, medium and weak QC models were compared with experimental VBM and CBM reported from X-ray photoemission spectroscopy (XPS), X-ray absorption spectroscopy (XAS) or photoluminescence (PL). Experimentally, the dimensions of the nanostructures were determined directly, by transmission electron microscopy (TEM), or indirectly, by x-ray diffraction (XRD) or by XPS. We found that crystalline materials are best described by a medium confinement model, while amorphous materials exhibit strong confinement regardless of the dimensionality of the system. Our results indicate that spatial delocalization of the hole in amorphous versus crystalline nanostructures is the important parameter determining the magnitude of the band gap expansion, or the strength of the quantum confinement. In addition, the effective masses of the electron and hole are discussed as a function of crystallinity and spatial confinement.

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Section: Quantum Wellmentioning

confidence: 99%

Quantum confinement in Si and Ge nanostructures

Barbagiovanni

Lockwood

Simpson

et al. 2012

Journal of Applied Physics

Self Cite

179

163

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“…The impact of surface structure of the silicon film on the efficiency of light emission is also investigated and we found that SiO 2 crystal that forms a strainless connection with a Si͑001͒ surface such as quartz enhances optical gain. Observations of light emissions from silicon nanostructures 1 such as porous silicon, 2 nanocrystals, 3 super lattices, 4 and quantum wells 5 have attracted much attention because of their potential applications in silicon photonics. 6 An efficient silicon light emitter would have a significant impact on electronics industry because it can be easily incorporated into the state-of-the-art silicon technology.…”

mentioning

confidence: 99%

Intrinsic optical gain of ultrathin silicon quantum wells from first-principles calculations

Suwa

Saito

2009

Phys. Rev. B

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Optical gains of ultrathin Si͑001͒ quantum wells are calculated from first principles, and found to be positive because of an intrinsic quantum confinement effect. The gain of the ultrathin silicon film is comparable to that of the bulk GaAs if the carrier density is large enough. The impact of surface structure of the silicon film on the efficiency of light emission is also investigated and we found that SiO 2 crystal that forms a strainless connection with a Si͑001͒ surface such as quartz enhances optical gain.

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“…[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.…”

Section: Introductionmentioning

confidence: 90%

“…In addition, the lateral dimensions of the nanostructures are too large (greater than the ∼ 5-nm Bohr radius for excitons in bulk silicon [19]) for strong confinement. If confinement plays a role in the observed emission, the confinement dimension is normal to the surface (as in the Si/SiO 2 superlattice [4]) and unchanged by an increase in the potential energy of the ion. An alternative explanation for the emission observed, that cannot be ruled out, is that the slow, highly charged ion impact induces a phase transformation in the impact volume to a structure (e.g.…”

Section: Figurementioning

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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Quantum Confined Luminescence inSi/SiO2Superlattices

Cited by 449 publications

References 18 publications

Quantum confinement in Si and Ge nanostructures

Quantum confinement in Si and Ge nanostructures

Intrinsic optical gain of ultrathin silicon quantum wells from first-principles calculations

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

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