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| 2. |
- Elsner, J., et al.
(författare)
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Deep acceptors trapped at threading-edge dislocations in GaN
- 1998
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 58:19, s. 12571-12574
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Tidskriftsartikel (refereegranskat)abstract
- Local-density-functional methods are used to examine the behavior of the oxygen defect, gallium vacancy, and related defect complexes trapped at threading-edge dislocations in GaN. These defects are found to be particularly stable at the core of the dislocation where oxygen sits twofold coordinated in a bridge position. VGa-ON is found to be a deep double acceptor, VGa-(ON)2 is a deep single acceptor, and VGa-(ON)3 at the dislocation core is electrically inactive. We suggest that the first two defects are responsible for a deep acceptor level associated with the midgap yellow luminescence band.
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| 3. |
- Elsner, J., et al.
(författare)
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Effect of oxygen on the growth of (101‾0) GaN surfaces : The formation of nanopipes
- 1998
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 73:24, s. 3530-3532
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Tidskriftsartikel (refereegranskat)abstract
- Local density-functional methods are used to examine the behavior of O and O-related defect complexes on the walls of nanopipes in GaN. We find that O has a tendency to segregate to the (10 1̄ 0) surface and identify the gallium vacancy surrounded by three oxygen impurities [VGa-(ON)3] to be a particularly stable and electrically inert complex. We suggest that during Stranski-Krastanow growth, when interisland spaces shrink, these defects reach a critical concentration beyond which further growth is prevented and nanopipes are formed
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| 4. |
- Elsner, J., et al.
(författare)
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Structural and electrical properties of threading dislocations in GaN
- 1997
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Ingår i: Defects in semiconductors. - : Trans Tech Publications Inc.. ; , s. 1203-1210
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Konferensbidrag (refereegranskat)abstract
- The atomic structures and electrical properties for threading screw and threading edge dislocations of wurtzite GaN are calculated within the local-density approximation. Both dislocations are electrically inactive with a band gap free from deep levels. These results are understood to arise from relaxed core structures which are similar to (1010) surfaces. The threading screw dislocations are found to be stable with an open-core whereas the threading edge dislocations possess filled cores.
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| 5. |
- Elsner, J, et al.
(författare)
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Theory of threading edge and screw dislocations in GaN
- 1997
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 79:19, s. 3672-3675
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Tidskriftsartikel (refereegranskat)abstract
- The atomic structures, electrical properties, and line energies for threading screw and threading edge dislocations of wurtzite GaN are calculated within the local-density approximation. Both dislocations are electrically inactive with a band gap free from deep levels. These results are understood to arise from relaxed core structures which are similar to (101̅ 0) surfaces.
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| 6. |
- Gutiérrez, R., et al.
(författare)
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The formation of nanopipes caused by donor impurities in GaN: A theoretical study for the case of oxygen
- 1999
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Ingår i: Philosophical Magazine Letters. - : Informa UK Limited. - 0950-0839 .- 1362-3036. ; 79:3, s. 147-152
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Tidskriftsartikel (refereegranskat)abstract
- Local density-functional methods are used to examine the behaviour of O and O-related defect complexes at {1010}-type surfaces in GaN. We find that O has a tendency to segregate to the (1010) surface and we identify the gallium vacancy surrounded by three oxygen impurities (VGa-(ON)3) to be a particularly stable and electrically inert complex. We suggest that these complexes impede growth at the walls of the nanopipes preventing them from growing in. Also, other donor-related defect complexes, in particular gallium vacancies surrounded by three silicon atoms as second nearest neighbours, are expected to have the same effect.
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| 7. |
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| 8. |
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| 9. |
- Jones, R, et al.
(författare)
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Interaction of oxygen with threading dislocations in GaN
- 1999
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Ingår i: Physica status solidi. A, Applied research. - 0031-8965 .- 1521-396X. ; 171:1, s. 167-173
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Tidskriftsartikel (refereegranskat)abstract
- A review is given of the results of first principles calculations used to investigate the structures and electronic properties of screw and edge dislocations in GaN. The atoms at the core of the full core screw dislocation possess heavily strained bonds leading to deep gap states. Removing the first shell of Ga and N atoms gives a screw dislocation with a small open core consisting of {101-0} type surfaces. Therefore open-core screw dislocations induce only shallow gap states. In the same way we found the core of the threading edge dislocation to be reconstructed without any deep states. The interaction of oxygen with the cores of open-core screw and edge dislocations is considered and it is found that the impurity has a strong tendency to be bound by Ga vacancies leading to three types of defect trapped in the strain field. We suggest that the most stable defect leads to a poisoning of growth centres on the walls of nanopipes.
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