Papers by Keyword: Vacancy Cluster

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Authors: Atsuo Kawasuso, Masashi Suezawa, Mitsuru Hasegawa, S. Yamaguchi, Koji Sumino
Authors: Atsuo Kawasuso, Masuyuki Hasegawa, Masashi Suezawa, S. Yamaguchi, Koji Sumino
Authors: Reino Aavikko, Kimmo Saarinen, Björn Magnusson, Erik Janzén
Abstract: Positron annihilation radiation Doppler broadening spectroscopy was used to study defects in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapour deposition (HTCVD). The Doppler broadening measurements show (i) that the measured samples contain vacancy clusters (ii) that the positron trapping to the clusters is increased in annealing (iii) that the chemical environment of the defects in the un-annealed samples is different from those of the annealed samples.
Authors: Adam Gali
Abstract: A brief overview about the recent progress in developing the methods to calculate the properties of defects in solids is given and some recent examples on vacancy-related defects in SiC are presented.
Authors: Yoshimasa Horii, Atsuo Kawasuso, Masuyuki Hasegawa, Masashi Suezawa, S. Yamaguchi, Koji Sumino
Authors: M.M. De Souza, Jonathan P. Goss
Abstract: A cluster comprising of indium, antimony and a vacancy in silicon is analysed using the planewave pseudopotential technique. This cluster has a strong binding energy that inhibits indium diffusion after high temperature anneal cycles. Difficulties associated with the simulation of a vacancy using the supercell approach are initially highlighted. In comparison, the indium-antimony-vacancy cluster reveals stronger distortions and reduction in relaxation volume. The indium atom in the relaxed cluster shows nearly six-fold coordination whereas the antimony atom acquires four neighbours. Due to the low symmetry of the centre, in constrast to the isolated vacancy there is no propensity for a Jahn-Teller effect. It gives rise to two defect levels in the bandgap.
Authors: A.I. Girka, A.D. Mokrushin, E.N. Mokhov, S.V. Svirida, A.V. Shishkin
Authors: Qiu Xu, Toshimasa Yoshiie, Takuya Nagasaka, Takeo Muroga
Abstract: To investigate the effect of impurites, such as O, N and C, on migration behavior of vacancies in several types of V-4Cr-4Ti vanadium alloy with different amount of impurites from 207wppm to 866wppm were irradiated with 28 MeV electrons using an electron linear accelerator at 100 K. After irradiation, positron lifetime measurements were carried out. Single vacancies were produced in all samples. The vacancy clusters were formed at 348 K and 433 K in samples with lowest and highest impurites, respectively. The temperature forming vacancy clusters incresased with increaisng amount of impurites. The vacancy migaration is depended on the amount of impurities rather than the kind of impurity.
Authors: Konrad Petters, J. Gebauer, F. Redmann, H.S. Leipner, Reinhard Krause-Rehberg
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