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| 2. |
- Paskova, T., et al.
(författare)
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Effect of high-temperature annealing on the residual strain and bending of freestanding GaN films grown by hydride vapor phase epitaxy
- 2006
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 88:14, s. 141909-
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Tidskriftsartikel (refereegranskat)abstract
- The effect of high-temperature high-pressure annealing on the residual strain, bending, and point defect redistribution of freestanding hydride vapor phase epitaxial GaN films was studied. The bending was found to be determined by the difference in the in-plane lattice parameters in the two faces of the films. The results showed a tendency of equalizing the lattice parameters in the two faces with increasing annealing temperature, leading to uniform strain distribution across the film thickness. A nonmonotonic behavior of structural parameters with increasing annealing temperature was revealed and related to the change in the point defect content under the high-temperature treatment. © 2006 American Institute of Physics.
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| 4. |
- Tuomisto, F, et al.
(författare)
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Dissociation of V-Ga-O-N complexes in HVPE GaN by high pressure and high temperature annealing
- 2006
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Ingår i: Physica status solidi. B, Basic research. - : Wiley. - 0370-1972 .- 1521-3951. ; 243:7, s. 1436-1440
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Tidskriftsartikel (refereegranskat)abstract
- We have used positron annihilation spectroscopy to study the high-pressure annealing induced thermal recovery of vacancy defects in free-standing GaN grown by hydride vapor phase epitaxy (HYPE). The results show that the in-grown Ga vacancy complexes recover after annealing at 1500-1700 K. Comparison of the experimental positron data with ab-initio calculations indicates that the Doppler broadening measurement of the electron momentum distribution is sensitive enough to distinguish between the N and O atoms surrounding the Ga vacancy. We show that the difference between the isolated V-Ga in electron irradiated GaN and the V-Ga-O-N complexes in highly O-doped GaN is clear, and the Ga vacancy related defect complexes that start dissociating at 1500 K can be identified as V-Ga-O-N pairs.
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| 5. |
- Tuomisto, T., et al.
(författare)
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Thermal stability of in-grown vacancy defects in GaN grown by hydride vapor phase epitaxy
- 2006
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 99:6
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Tidskriftsartikel (refereegranskat)abstract
- We have used positron annihilation spectroscopy to study the thermal behavior of different native vacancy defects typical of freestanding GaN grown by hydride vapor phase epitaxy under high pressure annealing at different annealing temperatures. The results show that the VGa - ON pairs dissociate and the Ga vacancies anneal out from the bulk of the material at temperatures 1500-1700 K. A binding energy of Eb =1.6 (4) eV can be determined for the pair. Thermal formation of Ga vacancies is observed at the annealing temperatures above 1700 K, indicating that Ga vacancies are created thermally at the high growth temperature, but their ability to form complexes such as VGa - ON determines the fraction of vacancy defects surviving the cooling down. The formation energy of the isolated Ga vacancy is experimentally determined. © 2006 American Institute of Physics.
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