Tight-binding molecular-dynamics simulations of amorphous silicon carbides

Иващенко, В. И.; Turchi, P. E. A.; Шевченко, В. И.; Ivashchenko, L. A.; Rusakov, G. V.

doi:10.1103/physrevb.66.195201

Cited by 26 publications

(27 citation statements)

References 27 publications

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“…The details of the computations with the orthogonal sp 3 s Ã TB scheme were described elsewhere. 40 In previous studies [40][41][42] it was shown that the set of TB two-center parameters that were used in the TB-MD simulations provided reasonable atomic and electronic structures for silicon-based amorphous alloys. In this work, the eigenvalues were calculated at the ⌫ point of the Brillouin zone, which is reasonable for a cubic cell with 512 atoms.…”

Section: Simulation Setupmentioning

confidence: 99%

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

2008

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The pressure-and indentation-induced phase transformations in crystalline ͑cd͒ and amorphous ͑a͒ silicon are studied by using molecular dynamics simulations based on the modified Tersoff potential. The sp 3 s Ã tight-binding scheme is employed to gain insight into the origin of the change in conductivity during nanoindentation. The Gibbs free energy calculations predict the following pressure-induced phase transitions: cd-Si → ␤-tin Si͑␤-Si͒ ͑11.4 GPa͒; cd-Si→ high density amorphous phase ͑HDA͒ ͑22.5 GPa͒; a-Si→ ␤-Si ͑2.5 GPa͒; a-Si→ HDA ͑8.4 GPa͒. Simulations of nanoindentation of crystalline silicon reveal discontinuities in the load-displacement curves. In the loading curves of the cd-Si ͑100͒ substrate, the pop-in is assigned to the appearance of the ␤-tin Si phase. During unloading, the pop-out is due to the formation of a low-density amorphous phase a-Si. The a-Si→ HDA transformation takes place during nanoindentation of a-Si in loading regime. Upon unloading the a-Si phase is preserved. The structural transformations in cd-Si and a-Si during nanoindentation are treated in terms of triaxial and uniaxial compressions of the respective bulk samples. A change in conductivity from semiconducting to metallic during nanoindentation of the cd-Si ͑100͒ and a-Si slabs is explained in terms of a transformation of the localized electronic states in the band gap region. The results are compared to those of available theoretical models and experiments.

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Section: Simulation Setupmentioning

confidence: 99%

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

2008

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“…[5][6][7][8][9] Meanwhile, theoretical investigations based on ab initio molecular dynamics ͑MD͒, tight-binding MD, and classical MD study or Monte Carlo simulations using various empirical potentials have also been carried out. 4,[10][11][12][13][14][15][16][17][18][19][20][21][22] Compared with the intensive reports about chemical or-der, the knowledge of topological SRO and MRO is limited. 4,[11][12][13]15,17,20 Although the tetrahedral unit is generally taken into account for a measure of SRO, the mediumrange picture, involving how these units are connected, is not yet clear, with a specific definition of MRO still wanted.…”

Section: Introductionmentioning

confidence: 99%

“…Controversial results are found in the literature. Several reports suggested that the topological amorphization is driven by a critical chemical disorder, 4,[11][12][13]17 while Rino et al 15 presented a topological disorder system without chemical disorder.…”

Section: Introductionmentioning

confidence: 99%

Effects of quench rates on the short- and medium-range orders of amorphous silicon carbide: A molecular-dynamics study

Xue

Niu

Shi

2008

Journal of Applied Physics

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On the influence of short and medium range order on the material band gap in hydrogenated amorphous silicon Amorphous silicon carbide ͑a-SiC͒ networks generated from melted SiC at various quench rates ͑from 10 14 to 5 ϫ 10 11 K / s͒ are studied with Tersoff potential based molecular-dynamics simulations. With the decreasing quench rates, dramatic changes are observed in chemical order, as well as in its topological orders over both short and medium ranges. The corresponding modification of topological short-range order is manifested not only by improvement of the characteristic tetrahedral configuration, but also by variation in the spatial distributions of the homonuclear bonds. On the other hand, the corresponding development over medium range gives rise to a more compact and more homogeneous structure. The essential mechanisms determining the atomic arrangements on both length scales are further explored. It is reasonable to argue that chemical order, as a function of the quench rate, should be mainly responsible for the topological features of a-SiC.

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“…However, Tersoff [12] argued that 15% of C atoms in the simulation of Finocchi et al were segregated into graphitic regions; excluding this graphitic regions from the total statistics, he inferred that a moderate chemical order exists in the structure. Ivashenko et al [14] pointed out that the final structure of a-Si 0.5 C 0.5 depends on the initial configuration and that a strong chemical order exists. Rino et al [15], performing molecular dynamics simulations with an effective two-and three-body interaction potential, concluded that neither carbon nor silicon structures are present under 3 Å ; so they state that there is a strong chemical order in these samples.…”

Section: Introductionmentioning

confidence: 99%

Simulating the structure of amorphous Si_0.5C_0.5 using Lin–Harris molecular dynamics

Mendoza

Valladares

2008

Molecular Simulation

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We have amorphised Si 0.5 C 0.5 by ab initio generating random networks with the experimental density of 2.75 g/cm 3 . Two types of crystalline supercells were used at the start: one was a diamond-like periodic supercell of 64 atoms, containing 32 carbons and 32 silicons, chemically ordered, amorphised using Fast Structure w , and the other was an fcc crystalline periodic supercell with 108 atoms, 54 carbons and 54 silicons, chemically ordered, amorphised using DMol 3 from the suite in Materials Studio 3.2 w . The amorphisation is made by heating the periodic samples to just below the melting point (the undermelt -quench approach), and then cooling them down to 0 K. Then the structures are relaxed by annealing and quenching, and finally a geometry relaxation is carried out. Our simulations show that Cerius 2w and Materials Studio 3.2 give equivalent results in general: atoms of one kind are almost completely surrounded by the atoms of the other kind. We also find that the two codes lead to total and partial radial distribution functions such that after weighting them with the corresponding experimental structure factors yield curves that are similar and comparable with experiment. Also CZC bonds with an average bond length of 1.35 Å are found.

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Tight-binding molecular-dynamics simulations of amorphous silicon carbides

Cited by 26 publications

References 27 publications

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

Effects of quench rates on the short- and medium-range orders of amorphous silicon carbide: A molecular-dynamics study

Simulating the structure of amorphous Si_0.5C_0.5 using Lin–Harris molecular dynamics

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Tight-binding molecular-dynamics simulations of amorphous silicon carbides

Cited by 26 publications

References 27 publications

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

Simulations of indentation-induced phase transformations in crystalline and amorphous silicon

Effects of quench rates on the short- and medium-range orders of amorphous silicon carbide: A molecular-dynamics study

Simulating the structure of amorphous Si0.5C0.5 using Lin–Harris molecular dynamics

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Simulating the structure of amorphous Si_0.5C_0.5 using Lin–Harris molecular dynamics