Density functional theory modelling of amorphous silicon

Cooper, N. C.; Goringe, C. M.; McKenzie, David R.

doi:10.1016/s0927-0256(99)00037-3

Cited by 37 publications

(25 citation statements)

References 19 publications

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“…With experiments on pure a-Si giving an average coordination number of 3.88 and non-vanishing density of states in the gap, the CRN model lacks some consistency with experiment. In contrast, heat and quench results in formation of under coordinated Si atoms, giving three and five fold coordinated Si, that is the dangling bond and the floating bond [18,37], and a nonzero mid-gap density of states [36] in consistency with experiments.…”

Section: Methods and Preparationsupporting

confidence: 64%

A first principles analysis of the effect of hydrogen concentration in hydrogenated amorphous silicon on the formation of strained Si-Si bonds and the optical and mobility gaps

Legesse

Nolan

Fagas

2014

Journal of Applied Physics

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Original citationLegesse, M., Nolan, M. and Fagas, G. (2014) ' AbstractIn this paper we use a model of hydrogenated amorphous silicon generated from molecular dynamics with density functional theory calculations to examine how the atomic geometry and the optical and mobility gaps are influenced by mild hydrogen oversaturation. The optical and mobility gaps show a volcano curve as the hydrogen content varies from undersaturation to mild oversaturation, with largest gaps obtained at the saturation hydrogen concentration.At the same time, mid-gap states associated with dangling bonds and strained Si-Si bonds disappear at saturation but reappear at mild oversaturation which is consistent with the evolution of optical gap. The distribution of Si-Si bond distances provides the key to the change in electronic properties. In the undersaturation regime the new electronic states in the gap arise from the presence of dangling bonds and strained Si-Si bonds, which are longer than the equilibrium Si-Si distance. Increasing hydrogen concentration up to saturation 2 reduces the strained bonds and removes dangling bonds. In the case of mild oversaturation the mid-gap states arise exclusively from an increase in the density of strained Si-Si bonds.Analysis of our structure shows that the extra hydrogen atoms form a bridge between neighbouring silicon atoms, thus increasing the Si-Si distance and increasing disorder in the sample.3

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Section: Methods and Preparationsupporting

confidence: 64%

A first principles analysis of the effect of hydrogen concentration in hydrogenated amorphous silicon on the formation of strained Si-Si bonds and the optical and mobility gaps

Legesse

Nolan

Fagas

2014

Journal of Applied Physics

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“…The energy and the bond-angle deviation of the well-relaxed structure agree very well with the experimental values (DFT: 0.14 eV, 9:7 ; Exp: 0.13 eV, 9:7 ). It is noted that the bond-angle deviation of our structure is much smaller than that made by Cooper et al [23]. Therefore, a conclusion for this inconsistency between experiment and simulation has yet to be reached.…”

Section: Article In Presscontrasting

confidence: 81%

“…On the other hand, from the classical and tight-binding molecular dynamics, the structure rich in floating bonds is predicted to be more stable than that rich in dangling bonds. In recent year, Cooper et al [23] have reached a conclusion that the structure rich in dangling bonds is more stable in the framework of the density functional theory (DFT) calculations. However, the bond-angle deviation of his structure is very large (15:2 ), due to insufficient annealing time.…”

Section: Article In Pressmentioning

confidence: 99%

Molecular dynamics study of homogeneous crystal nucleation in amorphous silicon

Izumi

Hara

Kumagai

et al. 2005

Journal of Crystal Growth

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“…Nosé thermostat assisted cooling with different rate followed the melting. We were able to achieve a slowest cooling rate up to 4×10 13 K/sec (5 K per each 300 steps) for all samples, the longest annealing time (about 50 ps with annealing) and equilibration compared to the previous AIMD simulations (see, for instance, [12,17] After the cooling, the thermostat was switched off and 40000 MD steps (10 ps)…”

Section: Theoretical Formalismmentioning

confidence: 98%

Temperature dependent vibrational spectra and bond dynamics in hydrogenated amorphous silicon

Kupchak

Gaspari

Shkrebtii

et al. 2008

Journal of Applied Physics

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We present a novel approach for parameter-free modeling of the structural, dynamical and electronic properties of non-crystalline materials based on ab-initio Molecular Dynamics, improved signal processing technique and computer visualization.The method have been extensively tested by investigating hydrogen and silicon dynamics in hydrogenated amorphous silicon (a-Si:H). By comparing the theoretical and experimental vibrational spectra we demonstrate how to relate vibrational properties to the structural stability, bonding and hydrogen diffusion. We extracted microscopic characteristics that cannot be obtained by other techniques, namely hydrogen migration and related bond switching, dangling bond passivation, low hydrogen activation energy, and a-Si:H stability in general, and we show, via the analysis of a test case, that our method provides a rigorous and realistic description of non-crystalline materials.We also demonstrate that this method offers the possibility of accessing other important macroscopic characteristics of amorphous silicon and can be used to model all the aspects of a-Si:H dynamics, including the detrimental Staebler-Wronski effect.

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Density functional theory modelling of amorphous silicon

Cited by 37 publications

References 19 publications

A first principles analysis of the effect of hydrogen concentration in hydrogenated amorphous silicon on the formation of strained Si-Si bonds and the optical and mobility gaps

A first principles analysis of the effect of hydrogen concentration in hydrogenated amorphous silicon on the formation of strained Si-Si bonds and the optical and mobility gaps

Molecular dynamics study of homogeneous crystal nucleation in amorphous silicon

Temperature dependent vibrational spectra and bond dynamics in hydrogenated amorphous silicon

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