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Now showing items 1 - 16 of 62

  • Recent advances in 4H-SiC epitaxy for high-voltage power devices

    Tsuchida, Hidekazu   Kamata, Isaho   Miyazawa, Tetsuya   Ito, Masahiko   Zhang, Xuan   Nagano, Masahiro  

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  • Fabrication of 4H-SiC PIN diodes on substrate grown by HTCVD method

    Tokuda, Yuichiro   Uehigashi, Hideyuki   Murata, Koichi   Tsuchida, Hidekazu  

    The device performance of 4H-SiC PiN diodes fabricated on a substrate produced by the HTCVD method was studied. A high-quality HTCVD substrate with a diameter of 3 in. was prepared as a specimen and fundamental PiN diodes were fabricated on the substrate. We confirmed that the diodes showed adequate operation for current-voltage characteristics in the initial state. While forward voltage is known to increase during forward operation for general PiN diodes, no increase in forward voltage was confirmed for the diodes fabricated on the HTCVD substrate even after forward current stress tests under current densities of 2500 A cm(-2). It was also found that the formation of stacking faults (SFs) in the drift layer was suppressed by utilizing the HTCVD substrate, which is contributed to the absence of an increase in forward voltage. The minority carrier lifetimes and impurity densities in the HTCVD substrate were evaluated to reveal the difference between the HTCVD and commercial substrates. Based on the evaluation the possible reasons for the absence of an increase in forward voltage and of SF formation are discussed (C) 2020 The Japan Society of Applied Physics
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  • Advances in Fast Epitaxial Growth of 4H-SiC and Defect Reduction

    Tsuchida, Hidekazu   Kamata, Isaho   Ito, Masahiko   Miyazawa, Tetsuya   Uehigashi, Hideyuki   Fukada, Keisuke   Fujibayashi, Hiroaki   Naitou, Masami   Hara, Kazukuni   Osawa, Hitoshi   Sugiura, Toshikazu   Kozawa, Takahiro  

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  • Microscopic FCA System for Depth-Resolved Carrier Lifetime Measurement in SiC

    Mae, Shinichi   Tawara, Takeshi   Tsuchida, Hidekazu   Kato, Masashi  

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    In this SiC diode (20), the impurity concentration of a second semiconductor layer portion (25A) having a thickness of less than 100 nm (for example, 50 nm) changes from a third impurity concentration (for example, 1 × 1020 cm-3) to an acceptor density of 1 × 1019 cm-3, said third impurity concentration being different by one or more orders of magnitude from an acceptor density of 1 × 1019 cm-3 that is a second impurity concentration. A discontinuous growth surface, where the impurity concentration changes abruptly, is formed in the second semiconductor layer portion (25A). This discontinuous growth surface serves as a recombination promoting surface for promoting the recombination of carriers, enabling a switching loss to be reduced. In addition, the carrier injection efficiency into a drift layer (23) is maintained high as compared with the case in which a pn-junction interface is used as the discontinuous growth surface, thereby enabling a steady loss to be prevented from increasing. This provides a bipolar semiconductor device, the switching loss of which can be reduced and the steady loss of which can be prevented from increasing.
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    In this production method for a SiC single crystal, a pedestal (9) is disposed inside a heating container (8) configuring a reaction chamber in which a SiC single crystal (20) is grown, a seed crystal (5) is adhered to the pedestal (9), the SiC single crystal is grown on the seed crystal by subjecting a starting-material gas to thermal decomposition in the heating container, the growth rate of the SiC single crystal is compared with a threshold range centred on a target value, if the growth rate is within the threshold range, the rotation speed of the seed crystal is maintained, in cases when the growth rate is greater than an upper-limit value of the threshold range, the rotation speed is maintained or reduced, and in cases when the growth rate is less than a lower-limit value of the threshold range, the rotation speed is increased.
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  • Evolution of Fast 4H-SiC CVD Growth and Defect Reduction Techniques

    Tsuchida, Hidekazu   Kamata, Isaho   Ito, Masahiko   Miyazawa, Tetsuya   Hoshino, Norihiro   Fujibayashi, Hiroaki   Ito, Hideki   Naito, Masami   Aoki, Hirofumi   Nishikawa, Koichi   Makino, Emi   Tokuda, Yuichiro   Kojima, Jun  

    This paper introduces our recent challenges in fast 4H-SiC epitaxial growth, high-speed crystal growth by a high-temperature gas source method and defect reduction. Enhanced growth rates in 4H-SiC epitaxial growth by high-speed wafer rotation and in a high-temperature gas source method by increasing the gas flow velocity are demonstrated. Trials and results of deflecting threading dislocations by patterned C-face 4H-SiC epitaxial growth are also shown.
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  • Deflection of threading dislocations in patterned 4H–SiC epitaxial growth

    Tsuchida, Hidekazu   Takanashi, Ryosuke   Kamata, Isaho   Hoshino, Norihiro   Makino, Emi   Kojima, Jun  

    Deflection of threading dislocations in patterned 4H-SiC epitaxial growth is investigated by applying multiple dry etching to create stair-like patterns growing toward < 1100> on < 1120> off-cut Si-face and C-face substrates. Forced deflection of most threading dislocations in the substrate is accomplished in the patterned C-face epitaxial growth; although no remarkable deflection of threading dislocations takes place in the patterned Si-face growth. The morphology of the patterned steps and behavior of threading and deflected dislocations are examined by optical microscopy and synchrotron X-ray topography, respectively. The interactions between the patterned steps and dislocations as well as the dependency of the deflection ratios of threading dislocations on the morphology of patterned steps are discussed. (C) 2014 Elsevier B.V. All rights reserved
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  • Fast growth of n-type 4H-SiC bulk crystal by gas-source method

    Hoshino, Norihiro   Kamata, Isaho   Tokuda, Yuichiro   Makino, Emi   Kanda, Takahiro   Sugiyama, Naohiro   Kuno, Hironari   Kojima, Jun   Tsuchida, Hidekazu  

    Fast growth of n-type 4H-SiC crystals was attempted using a high-temperature gas-source method. High growth rates exceeding 9 mm/h were archived at a seed temperature of 2550 degrees C, although the formation of macro-step bunching caused doping fluctuation and voids in the grown crystal. We investigated a trade-off between growth-rate enhancement and macro-step formation and how to improve the trade-off. By controlling the growth conditions, the growth of highly nitrogen-doped 4H-SiC crystals without the doping fluctuation and void formation were accomplished under a high growth rate exceeding 3 mm/h, maintaining the density of threading screw dislocations in the same level with the seed crystal. The influence of growth parameters on nitrogen incorporations into grown crystals was also surveyed. (C) 2017 Elsevier B.V. All rights reserved.
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  • Atomic characterization of nano-facet nitridation at SiC (1(1)over-bar00) surface

    Mori, Daisuke   Fujita, Yoshiki   Hirose, Takayuki   Murata, Koichi   Tsuchida, Hidekazu   Matsui, Fumihiko  

    Nitridation effectively reduces the density of defects at SiO2/SiC interfaces. The SiC (1 (1) over bar 00) face, which appears at the nano-trench structure on the (0001) and (000 (1) over bar) surfaces, is composed of Si- and C-facets. To understand the nitridation mechanism of this face, we investigate the atomic arrangement of N at SiC (1 (1) over bar 00) surface with high temperature annealing in N-2 ambient using x-ray photoelectron spectroscopy (XPS) and x-ray photoelectron diffraction (XPD). The N 1s spectrum indicates that N atoms cover about 5/6 of the monolayer and are bonded to Si atoms. The N 1s XPD pattern significantly differs from bulk Si 2p and the C 1s patterns, suggesting that the majority of N atoms occupy C sites at the topmost layer of the 4H-SiC substrate. Based on simulations of the N 1s spectrum and XPD pattern, we propose a local structure where N atoms replace C atoms at four different sites of the SiC (1 (1) over bar 00) surface and bond to three Si atoms. Published by AIP Publishing.
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  • Polarization of Photoluminescence from Partial Dislocations in 4H-SiC

    Hirano, Rii   Tsuchida, Hidekazu   Tajima, Michio   Itoh, Kohei M.   Maeda, Koji  

    Polarization characteristics of luminescence from partial dislocations (PDs) in 4H-SiC have been investigated by room-temperature photoluminescence (PL) imaging. The PLs from mobile PDs under optical excitation, which are 30 degrees-Si(g) PDs, and PDs tilted by 6 degrees from their Burgers vector (6 degrees-PDs) were found to be polarized perpendicular to their dislocation lines. In contrast, the PL from immobile 30 degrees-C(g) PDs was not polarized. The present results suggest that the carriers bound to the 30 degrees-Si(g) and 6 degrees-PDs have anisotropic wave functions and those bound to 30 degrees-C(g) PDs have isotropic wave functions. (C) 2013 The Japan Society of Applied Physics
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  • Formation of Extended Defects in 4H-SiC Epitaxial Growth

    TSUCHIDA, Hidekazu   KAMATA, Isaho   NAGANO, Masahiro  

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  • Development of a 150 mm 4H-SiC epitaxial reactor with high-speed wafer rotation

    Fujibayashi, Hiroaki   Ito, Masahiko   Ito, Hideki   Kamata, Isaho   Naito, Masami   Hara, Kazukuni   Yamauchi, Shoichi   Suzuki, Kunihiko   Yajima, Masayoshi   Mitani, Shinichi   Suzuki, Katsumi   Aoki, Hirofumi   Nishikawa, Koichi   Kozawa, Takahiro   Tsuchida, Hidekazu  

    A new type of 150 mm vertical 4H-SiC epitaxial reactor with high-speed wafer rotation has been developed. Multiple resistance heaters ensure uniform radial temperature distribution throughout a 150-mm-diameter wafer. Enhancement of the growth rates is realized by high-speed wafer rotation under a relatively high system pressure, and growth rates of 40-50 mu m/h are achieved on 4 degrees off 4H-SiC substrates, maintaining a low defect density and a smooth surface without macrostep bunching. Excellent thickness and doping uniformities are simultaneously obtained for a 150-mm-diameter wafer at a high growth rate of 50 mu m/h. (C) 2014 The Japan Society of Applied Physics
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  • Low-Pressure Fast Growth and Characterization of 4H-SiC Epilayers

    Tsuchida, Hidekazu   Ito, Masahiko   Kamata, Isaho   Nagano, Masahiro   Miyazawa, Tetsuya   Hoshino, Notihiro  

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    In this silicon carbide semiconductor film-forming apparatus, first to third gases are introduced into first to third separated chambers (41-43), respectively, through first to third introduction ports (31-33). The first and second gases are a Si material-containing gas and a C material-containing gas, and the third gas does not contain Si and C. The first and second gases are independently supplied to a growing space through first and second supply paths (41b, 42b) that extend from the first and second separated chambers, respectively. Furthermore, the third gas is introduced between the first and second gases through a third supply path (43b) from the third separated chamber.
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  • Hopping conduction range of heavily Al-doped 4H-SiC thick epilayers grown by CVD

    Ji, Shiyang   Eto, Kazuma   Yoshida, Sadafumi   Kojima, Kazutoshi   Ishida, Yuuki   Saito, Shingo   Tsuchida, Hidekazu   Okumura, Hajime  

    To outline the hopping conduction range, the electrical characteristics of CVD-grown heavily Al-doped 4H-SiC thick epilayers (2.0 x 10(19)-4.0 x 10(20) cm(-3)) were investigated in a wide temperature regime (20-900 K). It is found that, below 100 K, hopping conduction dominates the carrier transport for all epilayers, and the corresponding hopping conduction activation energy shows a maximum of similar to 30 meV at around 1.1 x 10(20) cm(-3). With increasing doping level, the temperature dependence of resistivity evolves and finally obeys the similar to 1/T-1/4 law in the entire temperature regime, which gives direct evidence of variable-range hopping conduction. (C) 2015 The Japan Society of Applied Physics
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