Hydrogenated Ge nanocrystals: band gap evolution with increasing size

Alfaro, Pedro; Miranda, Álvaro; Ramos, A. E.; Cruz‐Irisson, M.

doi:10.1590/s0103-97332006000300038

Cited by 11 publications

(4 citation statements)

References 13 publications

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“…6 illustrates that the energy band gap decreases towards its asymptotic bulk value with increasing cross-sectional diameter. The band gap of the nanowires increases monotonically with decreasing thickness, as has also been found in studies for semiconductors like Si or Ge [18,19]. These features of the band structures can be explained by a zone-folding argument of the bulk β-SiC bands onto the one-dimensional Brillouin zone of the wires.…”

Section: Resultssupporting

confidence: 74%

Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires

Miranda

Cuevas

Ramos

et al. 2009

JNanoR

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The effects on the electronic band structure of hydrogenated cubic silicon carbide (-SiC) nanowires of changes in the diameter and morphology are studied using a semiempirical sp3s* tight-binding approach applied to a supercell model. The results of the calculation of the electronic band structure and electronic density of states obtained are compared with those calculated by density functional theory within local density approximation only for the bulk of -SiC. As boundary conditions, we passivated all the Si and C dangling bonds with hydrogen atoms. The results show that although surface morphology modifies the band gap, the change is more systematic with the thickness variation. The energy band gap increases with decreasing diameter in all cases because of quantum confinement, but the scaling is dependent on the morphology (cross-section) of the -SiC nanowires. Finally, the calculations show a consistent asymptotical behavior to the crystalline limit when the width of the wires enlarges.

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Section: Resultssupporting

confidence: 74%

Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires

Miranda

Cuevas

Ramos

et al. 2009

JNanoR

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“…32 Zone-folding is best observed in structures where the band gap offset is minimized at the interface; otherwise, there will be significant band bending. SiGe/Si superlattices are typical candidates for zone-folding, 23 whereas isolated QDs are not ideal candidates for zone-folding 27 because of the significant band offset. Calculations have predicted a direct gap behaviour in SiC nanowires.…”

Section: Figmentioning

confidence: 99%

“…(4), corresponding to the magnitude of the indirect gap, which plays the role of the phonon. 27,28 This type of transition is called pseudo-direct. Theoretically, one can calculate the band gap energy for indirect transitions without considering the phonon momentum.…”

mentioning

confidence: 99%

Quantum confinement in Si and Ge nanostructures: Theory and experiment

Barbagiovanni

Lockwood

Simpson

et al. 2014

Applied Physics Reviews

200

132

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The role of quantum confinement (QC) in Si and Ge nanostructures (NSs) including quantum dots, quantum wires, and quantum wells is assessed under a wide variety of fabrication methods in terms of both their structural and optical properties. Structural properties include interface states, defect states in a matrix material, and stress, all of which alter the electronic states and hence the measured optical properties. We demonstrate how variations in the fabrication method lead to differences in the NS properties, where the most relevant parameters for each type of fabrication method are highlighted. Si embedded in, or layered between, SiO 2 , and the role of the sub-oxide interface states embodies much of the discussion. Other matrix materials include Si 3 N 4 and Al 2 O 3. Si NSs exhibit a complicated optical spectrum, because the coupling between the interface states and the confined carriers manifests with varying magnitude depending on the dimension of confinement. Ge NSs do not produce well-defined luminescence due to confined carriers, because of the strong influence from oxygen vacancy defect states. Variations in Si and Ge NS properties are considered in terms of different theoretical models of QC (effective mass approximation, tight binding method, and pseudopotential method). For each theoretical model, we discuss the treatment of the relevant experimental parameters. V

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“…Thus, a basic understanding of nc-Ge's dielectric properties is critical for designing devices of desired performance; for instance, the nc-Ge size dependency is correlated with the properties of resistance and capacitance, 6 photoluminescence, 7,8 and band gap. 9,10 However, the mechanism for dielectric properties has not yet been well understood despite the developed models such as quantum confinement, [11][12][13] nearly free electrons 14 and single-oscillator. 15 Wang and Zunger proposed that the changes to the dielectric function of the material are due to the surface of the quantum dot, not the overall size of the dot.…”

Section: Introductionmentioning

confidence: 99%

Size-suppressed dielectrics of Ge nanocrystals: skin-deep quantum entrapment

et al. 2012

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Although the dielectric behavior of nanostructured semiconductors has been intensively investigated, the physics behind observations remains disputed with possible mechanisms such as quantum confinement and dangling bond polarization. Here we show that theoretical reproduction of the measured dielectric suppression of Ge nanocrystals asserts that the dielectric suppression originates from the shorter and stronger bonds at the skin-deep surface, the associated local densification and quantum entrapment of energy. Coordination-imperfection induced local quantum entrapment perturbs the Hamiltonian that determines the band gap and hence, the process of electron polarization consequently.

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Hydrogenated Ge nanocrystals: band gap evolution with increasing size

Cited by 11 publications

References 13 publications

Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires

Effects of Morphology on the Electronic Properties of Hydrogenated Silicon Carbide Nanowires

Quantum confinement in Si and Ge nanostructures: Theory and experiment

Size-suppressed dielectrics of Ge nanocrystals: skin-deep quantum entrapment

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