Atomic relaxation and dynamical generation of ordered and disordered chemical vapour infiltration (CVI) SiC polytypes

Vignoles, Gérard L.

doi:10.1016/0022-0248(92)90092-w

Cited by 15 publications

(5 citation statements)

References 30 publications

(41 reference statements)

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“…In general, the greater the wurtzite component, the larger the band gap. Another important aspect for device engineering is the fact that different polytypes have different electronic effective masses [7][8][9]. The 3C SiC polytype has the highest electron mobility and saturation velocity because of reduced phonon scattering resulting from the higher symmetry.…”

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confidence: 99%

Electronic and optical properties of SiC polytypes using a transferable semi‐empirical tight‐binding model

Laref¹,

Laref

2008

Physica Status Solidi (b)

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The semi‐empirical tight‐binding (TB) method within the sp3s* basis has been used to investigate the electronic structure and optical properties of silicon carbide (SiC) polytypes. A TB model for the electronic structure calculations of the (4H, 6H and 8H) SiC polytypes is presented. The procedure involves the construction of the TB Hamiltonian of the (4H, 6H and 8H) SiC polytypes from the wurtzite one. The set of TB parameters is transferable to all hexagonal structures, which overcomes the need for extensive experimental data. The band structures for different SiC polytypes are used to determine the electron effective masses. The results are shown to be consistent with available experimental data and other theoretical calculations. Furthermore, the joint densities of states are calculated. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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mentioning

confidence: 99%

Electronic and optical properties of SiC polytypes using a transferable semi‐empirical tight‐binding model

Laref¹,

Laref

2008

Physica Status Solidi (b)

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“…The values of ln+\ and L"+i are such that the relative deformation, defined in ref 1 as dn+i = (Ln+l -Z"+i)/E"+i, is indeed positive. Its magnitude is more or less 0.6% in k and 1.0% in h, slightly higher than the data from ref 19.…”

Section: Methodology Of the Cluster Studymentioning

confidence: 96%

“…The energy and relaxation parameters of a cluster are evaluated according to the following procedure: (1) An "ideal" initial geometry is first determined for the cluster, where all bond angles have the ideal value of 109°28'. (2) The lengths Ln+1 and /"+1 are relaxed, while all the atomic positions of the lower bilayers are kept frozen, as well as the transversal crystallographic parameter a (epitaxy condition).…”

Section: Methodology Of the Cluster Studymentioning

confidence: 99%

A Cluster Approach for the Modeling of the Layer-by-Layer Growth of Silicon Carbide Polytypes

Vignoles¹,

Ducasse²

1995

J. Phys. Chem.

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A cluster approach has been designed in order to confirm the physical bases of a previously presented dynamical model for chemical vapor deposition-chemical vapor infiltration S i c growth (Vignoles, G. L. J. Cryst. Growth 1992, 118,430). The clusters consist of two or three Si-C bilayers; the relaxation of the bond lengths in the upper bilayer of the clusters simulates the impingement of a new bilayer on the crystal surface. The quantities relevant to the model (energies and optimized geometries) have been calculated at the semiempirical level. The use of regular series of clusters allowed us to obtain extrapolated values for infinite surfaces. Qualitative agreement has been obtained between the cluster calculations and the assumptions made for the dynamical model.

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“…However, only one model has been proposed for the growth of nonperiodic polytypes and the intergrowth of different ordered polytypes and disordered structure far from the equilibrium state (Vignoles 1992). The model proposed by Vignoles (1992) for SiC crystallization is based on the fine structure (or local structural deformation) of unit layers in different ordered polytypes and possible structural deformation during deposition of a new SiC layer at two possible positions. Vignoles (1992) proposed a qualitative logistic map (actually a circle map: Hao 1984, Baker andGollub 1990) for SiC crystals to account for long-period SiC polytypes, nonperiodic (chaotic) stacking, and intergrowth of different polytypes.…”

Section: The Genesis Of Nonperiodic Stacking In Biotitementioning

confidence: 99%

Periodic and Nonperiodic Stacking in Biotite from the Bingham Canyon Porphyry Copper Deposit, Utah

1995

Clays and clay miner.

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Fine-grained biotite crystals within primary actinolite from a quartz monzonite body of the Bingham Canyon porphyry copper deposit, Utah, consist of 1M, 5M~, and 1M d polytype structures. HRTEM images directly show the stacking sequences of ordered biotite polytypes, stacking faults in ordered polytypes, and stacking sequences in disordered polytypes, if the stacking vectors for the 2:1 layers involve only 0 ~ and + 120 ~ rotations. The most common type of stacking fault in the 1M biotite is a layer with-120 ~ rotation, followed by a layer with + 120 ~ rotation, which corresponds to one unit cell of the 2M1 polytype inserted in the 1M structure. Disordered (or semi-random) biotite is composed primarily of thin domains of the 1M and 2M~ polytypes, with stacking faults. The structure of a new 5-layer (5M~) polytype has been determined from SAED and HRTEM results. The stacking sequence of the polytype is [02022]. A model of structural oscillation among 1M, 2MI, and 3T structural states is proposed to interpret nonperiodic stacking sequences in biotite crystals formed during non-equilibrium crystallization. The model also provides qualitative insights into the structure of complex long-period polytypes and may help to explain intergrowths of ordered and disordered polytypes that form during crystallization far from the equilibrium state.

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Atomic relaxation and dynamical generation of ordered and disordered chemical vapour infiltration (CVI) SiC polytypes

Cited by 15 publications

References 30 publications

Electronic and optical properties of SiC polytypes using a transferable semi‐empirical tight‐binding model

Electronic and optical properties of SiC polytypes using a transferable semi‐empirical tight‐binding model

A Cluster Approach for the Modeling of the Layer-by-Layer Growth of Silicon Carbide Polytypes

Periodic and Nonperiodic Stacking in Biotite from the Bingham Canyon Porphyry Copper Deposit, Utah

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