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Article type: Cover
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Article type: Index
2003 Volume 30 Issue 2 Pages
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Hans J. Scheel
Article type: Article
2003 Volume 30 Issue 2 Pages
59-60
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Akinori Koukitu, Yoshihiro Kangawa
Article type: Article
2003 Volume 30 Issue 2 Pages
61-
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Noriyuki Kuwano
Article type: Article
2003 Volume 30 Issue 2 Pages
62-67
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Based on the results of microstructural characterization of GaN films by transmission electron microscopy, the roles of the substrate and the buffer layer in epitaxial growth have been reviewed in terms of crystal orientation relationship, lattice stress and lattice strain. In case of a large lattice-mis-match system where there are large differences in lattice parameters and crystal structure between the substrate and the growing crystal, the lattice strain at the hetero-interface should be considered in a different way from that in a "small lattice-mismatch" system. A buffer layer has some effects in addition to those of the substrate. Buffer layers of AlN and GaN are thought to have a similar effect on a sapphire substrate since they are in a category of large lattice-mismatch system, but they might have different effects in case of a small lattice-mismatch system as on a GaN-AlN template layer.
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Kenji Shiraishi, Jun-ichi Iwata, Atsushi Oshiyama
Article type: Article
2003 Volume 30 Issue 2 Pages
68-72
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ZrB_2 is a promising substrate for epitaxial growth of GaN, because its in-plane lattice constant is almost lattice-matched and the thermal expansion coefficient is very close to that of GaN. In this study, we theoretically investigate GaN epitaxy on ZrB_2 substrates by clarifying the atomic and electronic structures of GaN/ZrB_2 interfaces by first-principles calculations. Both GaN epilayer and ZrB_2 Substrate almost maintain the bulk structures when the epitaxial growth begins with the formation of N-Zr bonds. On the other hand, a remarkable zigzag structural change, which seems to deteriorate the lattice-matched nature of ZrB_2 Substrates, is found in the inter-facial B-plane when B-N bond formation occurs at the interface. These results indicate that suppression of B-N bond formation is a key point for the effective use of ZrB_2 as a substrate of GaN.
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Tsutomu Araki, Yasushi Nanishi
Article type: Article
2003 Volume 30 Issue 2 Pages
73-81
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Growth and properties of polycrystalline GaN are reviewed. GaN has been grown on an amorphous silica glass substrate by electron-cyclotron-resonance plasma-excited molecular beam epitaxy. GaN grown on silica glass is c-oriented polycrystalline consisting of columnar domains. Strong photoluminescence at near band edge of hexagonal GaN is observed from the polycrystalline GaN. Using nitridation of the substrate surface, polycrystalline GaN with improved c-axis orientation has been successfully grown on silica glass. This substrate nitridation gives rise to the formation of a silicon nitride layer, and results in a marked improvement in the uniformity of c-axis orientation and the surface morphology of subsequently grown polycrystalline GaN. These results demonstrate the potential of polycrystalline GaN grown on silica glass in the fabrication of low-cost, Iarge-size GaN-based devices.
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Toshihide Ide, Mitsuaki Shimizu, Xu-Qiang Shen, Kulandaivel Jeganathan ...
Article type: Article
2003 Volume 30 Issue 2 Pages
82-88
Published: June 25, 2003
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We show several technique for improving the GaN-film quality in radio frequency plasma assisted molecular beam epitaxy (rf-MBE). The first technique is Silicon (Si)-doping to the buffer layer. The effect of the Si-doping modifies the growth mode at the initial stage and the surface morphology of the GaN films. Using the Si-doped GaN buffer layer, the electron mobility of the two-dimensional electron gas at AlGaN/GaN heterointerfaces is improved due to the decrease of the number of electron scattering centers. The second technique is the reduction of the growth rate in rf-MBE-GaN growth on MOCVD-grown GaN templates. This technique changes the growth mode from spiral mode to step-flow mode. These techniques improve the GaN-film quality by changing the surface morphology due to the nucleation of the GaN grains during the initial growth. Therefore, the growth control involving these techniques as well as the quality and orientation of buffer layers, templates and substrates influence the quality of the GaN films.
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Kazuhide Kumakura, Masanobu Hiroki, Toshiki Makimoto, Naoki Kobayashi
Article type: Article
2003 Volume 30 Issue 2 Pages
89-95
Published: June 25, 2003
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We investigated the characteristics of GaN grown by metalorganic vapor phase epitaxy on SiN or Al_2O_3 masked substrates. The masks were formed by electron cyclotron resonance plasma deposition at room temperature. For regrown GaN using a SiN mask, threading dislocations from the underlayer GaN were terminated by the mask or were bending at the interface between regrown GaN and the mask from the transmission electron microscope (TEM) observation, resulting in the reduction of dislocation from 2×10^9 to 1.7×10^8cm^<-2>. Furthermore, no diffusion or segregation of Si atoms form the SiN mask was observed in secondary ion mass spectroscopy. For regrown GaN using a Al_2O_3 mask, the dislocations were also terminated at the mask. However, the horizontal dislocations were newly formed in the same manner for direct GaN growth on sapphire substrate. Moreover, the lines, similar to the structures observed as the inversion domain boundary in GaN by TEM observation, were also observed. To achieve higher quality regrown GaN using Al_2O_3 mask, it is necessary to clarify the formation mechanism for these dislocations.
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Fumio Kawamura, Tomoya Iwahashi, Masanori Morishita, Kunimichi Omae, M ...
Article type: Article
2003 Volume 30 Issue 2 Pages
96-103
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Large size and transparent GaN single crystal was successfully grown by Liquid Phase Epitaxy (LPE) method using alkali metal-based flux. This success was due to examinations of flux composition and to applying the LPE technique. GaN single crystal grown by LPE showed excellent photoluminescence characteristics and had extremely low dislocations. We review the processes of our attempts for growing large and transparent GaN single crystal and introduce the growth mechanisms.
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Yoshihiro Kangawa, Tomonori Ito, Yoshinao Kumagai, Akinori Koukitu
Article type: Article
2003 Volume 30 Issue 2 Pages
104-110
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Thermodynamic analyses were performed to understand the influence of lattice constraint from InN and GaN substrates on the relationship between input mole ratio R_<In> (=P_<In>^0/ (P_<In>^0 + P_<Ga>^0), where P^0_i is the input partial pressure of element i) and solid composition x in In_xGa_<1-x>N during molecular beam epitaxy (MBE) and metalorganic vapor phase epitaxy (MOVPE). For the both growth methods, the calculation results suggest that a compositionally unstable region is found at the InN-rich region for InGaN on GaN at higher temperatures while that for InGaN on InN can be seen at GaN-rich region due to the lattice constraint from the substrate. In case of the MOVPE, it is found that growth region of InGaN in the diagram related to V/III ratio and solid composition shrinks with increase of V/III ratio (increase of input partial pressure of NH_3). This is because the H_2 partial pressure produced by the decomposition of NH_3 increase at high V/III ratio (at high input partial pressure of NH_3).
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Takashi Tsurusako, Hitoshi Suzuki, Yoshio Saito, Chihiro Kaito
Article type: Article
2003 Volume 30 Issue 2 Pages
111-116
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In order to make clear the darkness of gold film, a recently developed method has been performed for gold film and Pb ultrafine particles. The reaction between gold film and Pb particles occurred above 100℃. The alloy formation has been formed near Pb particles in the gold film. The diffusion of Pb atoms into gold particles clearly observed. The darkness of gold film putting Pb particles is also verified by the irradiation of the sun light. The ultraviolet radiation is assisted the darkness of gold film. The darkness of gold film has been discussed as the problem of environment pollution which can be seen in gold temple in Kyoto Japan (Kinkakuji Temple).
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Tatau Nishinaga
Article type: Article
2003 Volume 30 Issue 2 Pages
117-
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Tadashi Ohachi, Yoshinori Furukawa, Taketoshi Hibiya
Article type: Article
2003 Volume 30 Issue 2 Pages
118-119
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[in Japanese]
Article type: Article
2003 Volume 30 Issue 2 Pages
120-
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[in Japanese]
Article type: Article
2003 Volume 30 Issue 2 Pages
120-121
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
122-123
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Appendix
2003 Volume 30 Issue 2 Pages
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Article type: Cover
2003 Volume 30 Issue 2 Pages
124-
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