| 1. |
- Polychroniadis, E, et al.
(författare)
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Microstructural characterization of very thick freestanding 3C-SiC wafers
- 2004
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248 .- 1873-5002. ; 263:1-4, s. 68-75
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Tidskriftsartikel (refereegranskat)abstract
- The microstructural characteristics of 300μm thick freestanding 3C-SiC wafers, provided by HOYA, were studied by transmission electron microscopy. The observed defects were mainly stacking faults (SFs), microtwins and inversion domain boundaries (IDBs). The defect density is reduced fast from the SiC/Si interface up to the first 20μm, and then it remains constant up to the surface, suggesting a defect growth and elimination mechanism. At the uppermost part of the film the distribution of the SFs is very inhomogeneous, large zones were completely free of SFs with the SFs mainly concentrating in areas where IDBs exist and their density was lower by more than one order of magnitude than the SFs. 3C-SiC 40μm thick layers were grown on the wafers by sublimation epitaxy. Optical micrographs of these layers exhibit macro-features different from the substrate, but still indicating large bands of SFs.
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| 2. |
- Tsiaoussis, I, et al.
(författare)
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Structural characterization of ZnO nanopillars grown by atmospheric-pressure metalorganic chemical vapor deposition on vicinal 4H-SiC and SiO2/Si substrates
- 2011
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Ingår i: JOURNAL OF APPLIED PHYSICS. - : American Institute of Physics. - 0021-8979 .- 1089-7550. ; 109:4, s. 043507-
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Tidskriftsartikel (refereegranskat)abstract
- The structural characteristics of ZnO nanocrystals epitaxially grown on p-type (0001) 4H-SiC substrates were studied by transmission electron microscopy (TEM). The nanocrystallites were grown by atmospheric-pressure metalorganic chemical vapor deposition. The ZnO nanocrystals were formed at terraces introduced by vicinal 4H-SiC substrates toward the [11 (2) over bar0] direction. They had the shape of hexagonal nanopillars, with their edges parallel to the andlt; 11 (2) over bar0 andgt; directions and a top c-plane facet, reflecting the crystal symmetry of ZnO. The free surface between the hexagonal nanopillars was covered by a very thin and highly defected epitaxial ZnO film, which strongly suggests the Stranski-Krastanov mode of growth. The ZnO/SiC interface was systematically studied by plane view TEM and cross sectional high resolution TEM. The residual strain in the thin continuous film as well as in the nanopillars was estimated from Moire patterns and by geometrical phase analysis. ZnO was also deposited on the SiO2/Si substrate for comparison. The films were polycrystalline exhibiting strong preferred orientation, with the c-axes of the grains almost perpendicular to the substrate resulting in the formation of nanopillars. The differences of nanopillar formation in the two substrates, 4H-SiC and SiO2 is also discussed.
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| 3. |
- Vouroutzis, N, et al.
(författare)
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Behavior of micropipes during growth in 4H-SiC
- 2002
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Ingår i: Materials Science Forum, Vols. 389-393. ; , s. 395-398
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Konferensbidrag (refereegranskat)abstract
- The disturbance of the growth steps in SiC epitaxy and the formation of stacking faults (SFs) in the vicinity of a micropipe were studied by Atomic Force Microscopy and Transmission Electron Microscopy. Shallow trenches are observed in front of the micropipes due to the distortion of the growth steps towards of the micropipe. The trenches are related with extended (1 (1) over bar 00) type SFs bounded by 1/6 < 11 (2) over bar1 > partial dislocations. These results are also supported by synchrotron X-ray topography.
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| 4. |
- Vouroutzis, N, et al.
(författare)
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Characteristics of planar defects in shallow trenches related to the presence of micropipes
- 2003
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Ingår i: Materials Science Forum, Vols. 433-436. ; , s. 277-280
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Konferensbidrag (refereegranskat)abstract
- The similarities of the trenches related with micropipes observed in 4H-SiC layers formed by sublimation epitaxy are compared with the line-shaped pits observed by optical microscopy in the vicinity of closing micropipes in 4H-SiC epilayers grown by the CVD method. The disturbance of the step-flow along the trenches and the related extended defects are discussed.
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| 5. |
- Yakimova, Rositsa, 1942-, et al.
(författare)
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Morphological features related to micropipe closing in 4H-SiC
- 2005
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 98:3, s. 34905-
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Tidskriftsartikel (refereegranskat)abstract
- The closing of micropipes during sublimation epitaxy has been studied. Shallow trenches are formed along the direction of the step-flow growth in the vicinity of closed micropipes. The trenches are related to a serious disturbance of the flowing steps and the formation of stacking faults in the (0001) basal plane as well as in the (1 1- 00) plane. A micropipe closes when the speed of the growth steps is higher than the spiral growth around the micropipe. This mechanism is related to a bending of the micropipe along the trench and the progressive emission of elementary screw dislocations along the trench. The morphology of the disturbed steps at the trenches and the related defects have been studied by transmission electron microscopy and atomic force microscopy. Supporting evidences are presented with optical micrographs from etched epilayers. Image forces, which are developed by the growth steps, stabilize the bending of the micropipes. The limitation of the bending is also discussed. © 2005 American Institute of Physics.
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