Papers by Keyword: Solution Growth

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Authors: Kenji Shibata, S. Harada, Toru Ujihara
Abstract: We realized the growth of 3C-SiC crystal on sapphire by solution growth method. The carbon deposition on a sapphire substrate before growth is the key point for this technology. This carbon layer plays a role to protect the dissolution of sapphire by Si solvent. Single crystal of 3C-SiC was grown on the whole surface of the sapphire substrate. Surprisingly, the 3C-SiC layer did not directly grown on the sapphire substrate. The single crystal 3C-SiC layer formed by the reaction between the deposited carbon and the Si wafer that is a solvent material below the melting point of silicon during heating process before the growth. The 3C-SiC grew on the 3C-SiC layer. In this process, the deposited carbon play another important role.
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Authors: Takeshi Mitani, Naoyoshi Komatsu, Tetsuo Takahashi, Tomohisa Kato, Toru Ujihara, Yuji Matsumoto, Kazuhisa Kurashige, Hajime Okumura
Abstract: We have investigated the solution growth under various Al-N co-doping conditions. Both p-type and n-type 4H-SiC were successfully grown under Al-N co-doping conditions, while using the effect of Al-addition to stabilize both growth surface and polytype. The doping and electrical properties were investigated systematically. Interaction between Al and N in the incorporation process and electrical property under heavily co-doped conditions were discussed.
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Authors: Kazuaki Seki, S. Harada, Toru Ujihara
Abstract: In this paper, we review our researches on the high-quality 3C-SiC bulk crystal growth. The polytype control and the suppression of defects are essential in the growth 3C-SiC on hexagonal SiC seed crystals. The growth polytype of SiC is usually controlled by the inheritance of the seed crystal. In contrast, we established kinetic polytype control in which the preferential growth of 3C-SiC can be achieved by the difference in the growth rates depending on supersaturation for the polytypes. In the growth of 3C-SiC, double positioning boundaries (DPBs) are often formed by the existence of twinned domain. The elimination of DPBs can be achieved utilizing the anisotropy of the step advance velocity.
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Authors: M. Arivanandhan, G. Rajesh, A. Tanaka, T. Ozawa, Yasunori Okano, Y. Inatomi, Yasuhiro Hayakawa
Abstract: As a preliminary experiment for the growth of InGaSb alloy crystals under microgravity at International Space Station (ISS), bulk crystal was grown under terrestrial condition using the same gradient heating furnace (GHF). Czochralski grown GaSb <111>B single crystal was used as a seed and feed crystals for the growth of InGaSb bulk crystals. During the growth, heat pulses were intentionally introduced periodically to create the growth striations. From the striations, the growth rate of the grown crystal was estimated. The results show that the growth rate was gradually increased from the beginning of the growth and became stable. On the other hand the In composition of the grown crystal decreased along the growth direction. From the In composition, the temperature gradient in the solution was estimated and it was almost the same of that fixed during the growth.
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Authors: Naoyoshi Komatsu, Takeshi Mitani, Tetsuo Takahashi, Tomohisa Kato, Kazuhisa Kurashige, Yuji Matsumoto, Toru Ujihara, Hajime Okumura
Abstract: In solution growth of 4H-SiC, we have investigated changes in macrostep height with addition of the Group III (B, Al, Ga), Group IV (Ge, Sn), Group V (N) elements, and transition metals (Ti, V, Cr, Ni) to Si solvents, in order to find additives improving severe step bunching which often occurs during growth. The addition of Al, B, Sn, N, and V decreased the average macrostep height compared with the crystal grown with Si solvents. The addition of Al, B, Sn, N, and V suppressed the generation of trench-shaped surface defects in long-term growth of 10 hours. This result demonstrated that the addition of Al, B, Sn, N, and V has an advantage to achieve high quality bulk crystal growth from solution.
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Authors: Takeshi Mitani, Masayuki Okamura, Tetsuo Takahashi, Naoyoshi Komatsu, Tomohisa Kato, Hajime Okumura
Abstract: Void formation in 4H-SiC crystals grown from solution has been investigated by secondary ion mass spectrometry and Raman scattering. It becomes clear that ambient Ar gas is filled in voids and the solvent (Si) partially remains. The result indicates that Ar dissolved in the solvent vaporizes and forms bubbles. The trapped bubbles at the crystal growth front are considered to be incorporated in the growing crystal as voids. We also have developed following methods for suppression of the void formation; (1) dipping seed crystals so that the growth front faces upward, (2) growth under He atmosphere, and (3) the high temperature treatment of the solvent before crystal growth.
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Authors: Toru Ujihara, Shigeta Kozawa, Kazuaki Seki, Alexander, Yuji Yamamoto, S. Harada
Abstract: Solution growth is considered to be a powerful method for high quality SiC crystals. This work reports that the conversion process from a threading screw dislocation into a few Frank partial dislocations in basal planes was investigated by synchrotron X-ray topography. This process was effectively assisted by step-flow growth on off-oriented (0001) seed crystals. The Frank partials were not extended into the crystal grown toward the [0001] direction perpendicular to the basal plane. Thus, the conclusion of this study suggests the use of off-oriented seed crystal is important to improve crystal quality.
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Authors: Kazuhiko Kusunoki, Kazuhito Kamei, Y. Ueda, S. Naga, Y. Ito, Mitsuhiro Hasebe, Toru Ujihara, Kazuo Nakajima
Abstract: The growth of 6H-SiC crystal from Si-Ti-C ternary solution was conducted under the temperature gradient and the crystalline quality evaluations of the grown crystals were carried out. 6H-SiC(0001) on-axis pvt-grown crystal was used as a seed crystal. Micropipes in the seed crystal were terminated during the solution growth and 28mm􀊷28mm self-standing micropipe-free SiC crystals were obtained. The quality of the grown crystals was investigated by SIMS, high-resolution x-ray diffraction and molten KOH etching. The content of residual impurities in the SiC were very low. The X-ray 􀐢-rocking curves of the solution grown SiC showed single peak with high peak intensity ,while that of the seed crystal showed several peaks due to the misoriented domains. Moreover, it was found that the number of etch-pit in the grown crystal is much less than that in the seed crystal and it decreases with the increase of the growth thickness. These results indicate that the crystalline quality of grown crystal was significantly improved during the solution growth.
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Authors: Kazuhito Kamei, Kazuhiko Kusunoki, Nobuyuki Yashiro, Nobuhiro Okada, Koji Moriguchi, H. Daikoku, M. Kado, H. Suzuki, H. Sakamoto, T. Bessho
Abstract: Crystallinity of 4H-SiC bulk crystal obtained by solution growth technique was characterized mainly by KOH etching of the off-ground and serially ground specimen. Marked reduction of basal plane dislocation, threading edge and screw dislocations during the growth of on-axis crystal was confirmed. Cross-sectional TEM observation revealed the rapid reduction behavior of threading dislocations microscopically. AFM observation of as-grown morphology showed that screw dislocation dipoles is related to the reduction of threading screw dislocations and single domain formation, which is essential for establishing the high crystallinity.
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Authors: Shigeta Kozawa, Kazuaki Seki, Alexander, Yuji Yamamoto, Toru Ujihara, Yoshikazu Takeda
Abstract: We investigated dislocation behavior in the crystal grown on 6H-SiC (0001) by solution method using synchrotron X-ray topography and thermal chlorine etching. It was confirmed that basal plane dislocation was not newly formed in the grown layer. In addition, the positions of threading screw dislocations (TSDs) were displaced and some of them disappeared in the grown layer. This displacement was caused by the bending of the TSDs during growth.
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