| 21. |
- Iwata, H., et al.
(author)
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Electronic properties of stacking faults in 15R-SiC
- 2003
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In: Silicon carbide and related materials. - Uetikon-Zuerich : Trans Tech Publications Inc.. - 0878499202 ; , s. 531-534
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Conference paper (peer-reviewed)abstract
- A first-principles calculation of stacking faults in 15R-SiC is reported. All the geometrically distinguishable stacking faults which can be introduced by the glide of partial dislocations in (0001)-basal planes are investigated: there exist as many as five different stacking faults in 15R-SiC. Electronic properties and stacking fault energies of these extended defects are studied based on the density functional theory in the local density approximation. Stacking fault energies are also calculated using the axial next nearest neighbor Ising (ANNNI) model.
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| 22. |
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| 23. |
- Iwata, H, et al.
(author)
-
Electronic structure of twin boundaries in 3C-SiC, Si and diamond
- 2002
-
In: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 433-4, s. 527-530
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Journal article (peer-reviewed)abstract
- We report on a first-principles band structure calculation of twin boundaries in 3C-SiC, Si, and diamond, based on the density functional theory in the local density approximation. It is found that the electron wave functions belonging to the conduction and valence band edge states in 3C-SiC tend to be localized almost exclusively on different sides of the boundaries, while there is no such feature in Si and diamond. We have interpreted these localization and segregation phenomena as a consequence of the electrostatic field caused by the spontaneous polarization due to the hexagonal symmetry around twin boundaries. A mechanism for the creation of twin boundaries, i.e., propagation of partial dislocations in neighboring basal planes, has been investigated using total energy calculations, and it has been realized that the double-intrinsic-stacking-fault structure in 3C-SiC, coinciding with the extrinsic stacking faults, is much energetically favored.
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| 24. |
- Iwata, H., et al.
(author)
-
Electronic structure of twin boundaries in 3C-SiC, Si and diamond
- 2003
-
In: Silicon carbide and related materials 2002. - Uetikon-Zuerich : Trans Tech Publications Inc.. - 878499202 ; , s. 527-30
-
Conference paper (peer-reviewed)abstract
- We report on a first-principles band structure calculation of twin boundaries in 3C-SiC, Si, and diamond, based on the density functional theory in the local density approximation. It is found that the electron wave functions belonging to the conduction and valence band edge states in 3C-SiC tend to be localized almost exclusively on different sides of the boundaries, while there is no such feature in Si and diamond. We have interpreted these localization and segregation phenomena as a consequence of the electrostatic field caused by the spontaneous polarization due to the hexagonal symmetry around twin boundaries. A mechanism for the creation of twin boundaries, i.e., propagation of partial dislocations in neighboring basal planes, has been investigated using total energy calculations, and it has been realized that the double-intrinsic-stacking-fault structure in 3C-SiC, coinciding with the extrinsic stacking faults, is much energetically favored.
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| 25. |
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| 26. |
- Iwata, H.P., et al.
(author)
-
Ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC
- 2003
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:8, s. 4972-4979
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Journal article (peer-reviewed)abstract
- Ab initio supercell calculations of cubic inclusions in 6H-SiC are performed. The cubic inclusions can be created in perfect 6H-SiC by the propagation of successive partial dislocations having the same Burgers vector in neighboring basal planes, i.e., multiple stacking faults. We have studied the electronic structures and the total energies of 6H-SiC single crystals that contain one, two, three, and four stacking faults, based on density functional theory in local density approximation. Our total energy calculations have revealed that the second stacking fault energy in 6H-SiC is about six to seven times larger than that of an isolated stacking fault, which is actually opposite the trend recently obtained for 4H-SiC [J. Appl. Phys. 93, 1577 (2003)]. The effects of spontaneous polarization on the electronic properties of stacking disorders are examined in detail. The calculated positions of the quantum-well-like localized bands and stacking fault energies of 3C inclusions in 6H-SiC are compared with those previously determined in 4H-SiC, and the possibility of local hexagonal to cubic polytypic transformations is discussed in light of the formation energy and quantum-well action.
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| 27. |
- Iwata, H P
(author)
-
Determination of the in-plane anisotropy of the electron effective mass tensor in 6H-SiC
- 2003
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:4, s. 598-600
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Journal article (peer-reviewed)abstract
- An experimental evidence for the strong in-plane anisotropy of the electron effective mass tensor in 6H-SiC is reported. Furthermore, two components of the mass tensor in 6H-SiC, m(M-Gamma)* and m(M-K)*, have been resolved by making a theoretical bridge between Hall effect measurements and cyclotron resonance experiments, based on the Boltzmann transport equation. The method to resolve the in-plane effective mass components is also applied for 4H-SiC, which have already been resolved by cyclotron resonance. The values determined by our method are fully consistent with available experiments and calculations.
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| 28. |
- Iwata, H.P., et al.
(author)
-
Energies and electronic properties of isolated and interacting twin boundaries in 3C-SiC, Si, and diamond
- 2003
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X .- 0163-1829. ; 68:11, s. 113202-
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Journal article (peer-reviewed)abstract
- First-principles calculations of twin boundaries in 3C-SiC, Si, and diamond are performed, based on the density-functional theory in the local density approximation. We have investigated the formation energies and electronic properties of isolated and interacting twin boundaries. It is found that in 3C-SiC, interacting twin boundaries which are separated by more than two Si-C bilayers are actually energetically more favorable, implying a relatively frequent appearance of these defects. The effect of the spontaneous polarization associated with the hexagonal symmetry around twin boundaries is also studied, and we have observed that the wave functions belonging to the conduction- and valence-band edge states in 3C-SiC tend to be localized almost exclusively on different sides of the faulted layers, while there is no such feature in Si or diamond.
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| 29. |
- Iwata, H, et al.
(author)
-
Stacking fault - Stacking fault interactions and cubic inclusions in 6H-SiC : an ab initio study
- 2002
-
In: Materials Science Forum, Vols. 433-436. ; , s. 921-924
-
Conference paper (peer-reviewed)abstract
- We report on a first-principles supercell calculation of cubic inclusions in 6H-SiC. Motions of successive partial dislocations having the same Burgers vector in the basal planes can lead to a 3C-like region in the perfect 6H-SiC crystal, which corresponds to multiple stacking faults. We have calculated the electronic structures and the total energies of 6H-SiC crystals containing in stacking faults (m=1-4) in the adjacent basal planes, based on the density functional theory in the local density approximation. It has been found that 3C-like sequences in the 6H-host crystals can act as planar quantum wells, in which conduction band electrons can be confined. The total energy calculations using both the supercell method and the axial next nearest neighbor Ising model (ANNNI) have revealed that the 2nd stacking fault energy in 6H-SiC is about 6 times larger than that of an isolated stacking fault.
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| 30. |
- Iwata, H., et al.
(author)
-
Stacking fault - stacking fault interactions and cubic inclusions in 6H-SiC : an ab initio study
- 2003
-
In: Silicon carbide and related materials. - Uetikon-Zuerich : Trans Tech Publications Inc.. - 0878499202 ; , s. 921-924
-
Conference paper (peer-reviewed)abstract
- We report on a first-principles supercell calculation of cubic inclusions in 6H-SiC. Motions of successive partial dislocations having the same Burgers vector in the basal planes can lead to a 3C-like region in the perfect 6H-SiC crystal, which corresponds to multiple stacking faults. We have calculated the electronic structures and the total energies of 6H-SiC crystals containing m stacking faults (m=l-4) in the adjacent basal planes, based on the density functional theory in the local density approximation. It has been found that 3C-like sequences in the 6H-host crystals can act as planar quantum wells, in which conduction band electrons can be confined. The total energy calculations using both the supercell method and the axial next nearest neighbor Ising model (ANNNI) have revealed that the 2nd stacking fault energy in 6H-SiC is about 6 times larger than that of an isolated stacking fault.
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