| 1. |
- Iwata, H.P., et al.
(författare)
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Ab initio study of 3 C inclusions and stacking fault-stacking fault interactions in 6H-SiC
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 94:8, s. 4972-4979
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Iwata, H P
(författare)
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Determination of the in-plane anisotropy of the electron effective mass tensor in 6H-SiC
- 2003
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 82:4, s. 598-600
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Iwata, H.P., et al.
(författare)
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Effective masses of two-dimensional electron gases around cubic inclusions in hexagonal silicon carbide
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X .- 0163-1829. ; 68:24, s. 245309-1
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this article is to determine the two-dimensional effective mass tensors of electrons confined in thin 3C wells in hexagonal SiC, which is a first step in the understanding of in-plane electron motion in the novel quantum structures. We have performed ab initio band structure calculations, based on the density functional theory in the local density approximation, for single and multiple stacking faults leading to thin 3C-like regions in 4H- and 6H-SiC and deduced electron effective masses for two-dimensional electron gases around the cubic inclusions. We have found that electrons confined in the thin 3C-like layers have clearly heavier effective masses than in the perfect bulk 3C-SiC single crystal.
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| 4. |
- Iwata, H.P., et al.
(författare)
-
Energies and electronic properties of isolated and interacting twin boundaries in 3C-SiC, Si, and diamond
- 2003
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X .- 0163-1829. ; 68:11, s. 113202-
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Tidskriftsartikel (refereegranskat)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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