Papers by Keyword: Silicon

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Authors: Valentin V. Emtsev, Boris A. Andreev, Gagik A. Oganesyan, D.I. Kryzhkov, Andrzej Misiuk, Charalamos A. Londos, M.S. Potsidi
Abstract: Effects of compressive stress on oxygen agglomeration processes in Czochralski grown silicon heat treated at T= 450OC, used as a reference temperature, and T= 600OC to 800OC are investigated in some detail. Compressive stresses of about P= 1 GPa lead to enhanced formation of Thermal Double Donors in materials annealed over a temperature range of T= 450OC – 600OC. It has been shown that the formation of thermal donors at T= 450OC under normal conditions and compressive stress is accompanied with loss of substitutional boron. In contrast, the concentration of the shallow acceptor states of substitutional boron in silicon annealed under stress at T≥ 600OC remains constant. An enhancement effect of thermal donor formation is gradually weakened at T≥ 700OC. The oxygen diffusivity sensitive to mechanical stress is believed to be responsible for the observed effects in heat-treated silicon.
Authors: Hannes Grillenberger, Andreas Magerl
Abstract: Oxygen precipitation in silicon has been studied in-situ by high energy X-ray diffraction. A gain of diffracted intensity is expected if an ideal crystal is distorted by growing precipitates as the diffraction mode changes from a dynamical to a more kinematical one. Irreversible changes in the intensity of a 220 and a 400 Bragg peak are detected for Czochralski grown samples only, but not in a float zone grown reference crystal. Thus, these changes are attributed to oxygen precipitation, which is confirmed by a subsequent classical ex-situ characterization. Further, the changes of the intensities of the two measured Bragg peaks are compared to each other to get the level of change in the diffraction mode from a dynamical to a kinematical one. The detection limit of the specific setup is estimated via a simulation of the defect inventory to correspond to a precipitate diameter of 50nm with the density of 6.9•109 1/cm3. The diffraction experiments are done with polychromatic and divergent X-rays generated by a laboratory source, albeit with high energy. This results in a simple and accessible setup for the characterization of oxygen precipitates.
Authors: Johannes Will, Alexander Gröschel, Christoph Bergmann, Andreas Magerl
Abstract: The measurement of Pendellösungs oscillations was used to observe the time dependent nucleation of oxygen in a Czochralski grown single crystal at 750°C. It is shown, that the theoretical approach of the statistical dynamical theory describes the data well. Within the framework of this theory it is possible to determine the static Debye-Waller-factor as a function of the annealing time by evaluating the mean value of the Bragg intensity and the period length. The temperature influence on the Pendellösungs distance was corrected for by measurement of a Float-zone sample at the same temperature.
Authors: Yusuke Nakashima, Michiyo Honda, Toshiisa Konishi, Minori Mizumoto, Mamoru Aizawa
Abstract: In our previous study, silicon-containing hydroxyapatite (Si-HAp) powder was prepared via an aqueous precipitation reaction. The Si-HAp powders were synthesized with desired Si contents (0, 0.4, 0.8, 1.6, and 2.4 mass%) as a nominal composition. Another previous study in our group demonstrated surface-modification of HAp powder with inositol phosphate (IP6) enhanced the compressive strength of apatite cement. Thus, to fabricate the cements with higher bioactivity, the above Si-HAp powders were surface-modified with IP6 (IP6-Si-HAp). The IP6-Si-HAp cements with various Si contents were fabricated by mixing with pure water at the powder/liquid ratio of 1/0.4 [w/v]. In order to clarify biocompatibility of the IP6-Si-HAP cements in the present work, MC3T3-E1 cells as a model of osteoblast were seeded on the cement specimens. As for the numbers of cells cultured on the IP6-Si-HAp cements, the substitution of lower levels of Si into HAp lattice did not greatly influence the cell proliferation. However, the substitution of Si amount over 0.8 mass% enhanced the cell proliferation. Especially, the IP6-Si-HAp cement with the Si content of 2.4 mass% showed excellent cell proliferation among examined specimens. Therefore, to fabricate the cements with higher bioactivity, it is necessary to control the amount of Si in the IP6-Si-HAp cements. The usage of these IP6-Si-HAp cements may make it possible to fabricate the cements with higher bioactivity, compare to conventional pure HAp cements.
Authors: N.Yu. Arutyunov, V.Yu. Trashchakov
Authors: Jean François Michaud, Marc Portail, Thierry Chassagne, Marcin Zielinski, Daniel Alquier
Abstract: The aim of this paper is to review the recent developments conducted by our groups for the achievement of 3C-SiC based heterostructures compatible for MEMS applications. It deals with different aspects, from the influence of the defects generated at the 3C-SiC/Si interface on the mechanical properties to the elaboration of new multilayered structures, required for specific applications like, for example, Atomic Force Microscopy.
Authors: Yutaka Furubayashi, Takafumi Tanehira, Kei Yonemori, Nobuhide Seo, Shinichiro Kuroki
Abstract: We propose 3-D integration of Peltier device onto a power device. In order to transport a heat from the power device, as a suitable material of the Peltier device, silicon was adopted because of its high Seebeck coefficient, high thermal conductivity, and applicability to semiconductor process. Bulk Si-based Peltier devices with conventional shape showed an active thermal transport over a Joule heat at the operation current less than 5 A. 3-D integration of 4H-SiC-based Schottky barrier diodes and Si-based film Peltier device, separated by intrinsic SiC layer, was realized by using conventional Si-based process flow.
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