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364 results on '"Heera, V."'

151. P implantation into preamorphized germanium and subsequent annealing: Solid phase epitaxial regrowth, P diffusion, and activation

Author

Posselt, M., primary, Schmidt, B., additional, Anwand, W., additional, Grötzschel, R., additional, Heera, V., additional, Mücklich, A., additional, Wündisch, C., additional, Skorupa, W., additional, Hortenbach, H., additional, Gennaro, S., additional, Bersani, M., additional, Giubertoni, D., additional, Möller, A., additional, and Bracht, H., additional

Published
2008
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156. Magic matching in semiconductor heterojunctions.

Author

Cullis, A. G., Hutchison, J. L., Pécz, B., Barna, Á, Heera, V., and Skorupa, W.

Abstract

Matching of m crystal planes of a grown layer to n planes of the substrate is observed in many cases, when the difference in the lattice parameters is large. This kind of magic matching is explained by coincidence planes. Two examples are shown in this paper. SiC grains perfectly oriented to the substrate were prepared by high temperature ion implantation of Si into natural diamond. Considering the (111) lattice planes and the cases when 5 planes of SiC match to 6 planes in diamond, or 4 planes of SiC match to 5 planes in diamond, the misfit is reduced to about 2% in both cases having opposite signs. High resolution images taken at the SiC/diamond interface were investigated and both of the above mentioned domains were found. When we consider the regular distribution of the above two domains, i.e. matching of 9 SiC lattice planes to 11 diamond planes a misfit value below 0.1% is obtained. This explains how the ion beam synthesised SiC can grow epitaxially despite the huge difference in lattice parameters. GaN synthesised in GaAs by ion implantation is presented as another example where magic matching of 5:4 reduces the misfit to 0.8%. That value is low enough to be compensated by elastic deformation of the lattice, therefore the insertion of another domain is not needed. [ABSTRACT FROM AUTHOR]

Published
2005
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186. Diamond formation by carbon implantation into cubic silicon carbide

Author

Weishart, H., Heera, V., Eichhorn, F., Pécz, B., Toth, L., and Skorupa, W.

Subjects
*DIAMONDS, *MICROSTRUCTURE, *ION bombardment, *SILICON carbide
Abstract

Cubic SiC is implanted with carbon ions at 600, 900, 1100 and 1200 °C. X-ray diffraction and transmission electron microscopy revealed the influence of implantation temperature and dose rate on the formation of graphite and diamond precipitates, respectively. The high dose carbon implantation at 600 °C yields graphite already in a textured form. Spherical diamond grains, which are always epitaxial to the SiC, are found in samples implanted at 900 °C or higher. Increasing the dose rate leads to formation of graphite instead of diamond at 900 °C as well. Hence, a critical temperature for diamond evolution exists, which depends on dose rate. Size and shape of the formed diamond precipitates is not influenced by dose rate within the investigated range. Increasing the fluence results in bigger diamond nanocrystals, which are bordered by facets. [Copyright &y& Elsevier]

Published
2004
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187. Ion beam synthesis of diamond-SiC-heterostructures

Author

Weishart, H., Heera, V., Eichhorn, F., Pecz, B., Barna, A., and Skorupa, W.

Subjects
*SILICON carbide, *ION bombardment
Abstract

Nanocrystals of silicon carbide were synthesized inside natural diamond using high dose silicon implantation. In order to retain the diamond structure implantation was done at 900 °C. The samples were subsequently annealed in an rf-heated furnace at 1500 °C for 10 min. X-Ray diffraction (XRD), IR absorption spectrometry and high-resolution cross-sectional transmission electron microscopy (HRTEM) are used to investigate formation and structure of SiC nanocrystallites in the implanted diamond. Raman spectroscopy contributed to trace implantation-induced destruction of the diamond. A first characterization of the electrical properties of the implanted and annealed samples is done by four-point probe measurements. The results indicate a highly conductive, buried layer inside the diamond. This layer contains cubic SiC nanocrystals, which are perfectly aligned with the diamond lattice. However, when fluence exceeds a critical value of 5.3×1017 Si+ cm−2, the diamond is irreversibly damaged and defect conduction type dominates. [Copyright &y& Elsevier]

Published
2003
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