| Project/Area Number |
18360321
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
TSUDA Osamu National Institute for Materials Science, Optronic materials center, NIMS adjunct researcher (10242041)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Kenji National Institute for Materials Science, Optronic materials center, Senior researcher (20343840)
TANIGUCHI Takashi National Institute for Materials Science, Advanced nano materials laboratory, Group leader (80354413)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥13,680,000 (Direct Cost: ¥12,300,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2007: ¥5,980,000 (Direct Cost: ¥4,600,000、Indirect Cost: ¥1,380,000)
Fiscal Year 2006: ¥7,700,000 (Direct Cost: ¥7,700,000)
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| Keywords | hexagonal boron nitride / deep ultra violet emission / cathodoluminescence / room temperature / exciton / CVD / 自由励起子 |
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| Research Abstract |
Hexagonal boron nitride (hBN) is one of promising materials which emit ultraviolet (UV) light due to its intense exciton luminescence at 215 nm at room temperature. Since the size of hBN crystals, which are conventionally grown by the high temperature high pressure method (HPHT), is limited at most to a few mm, an alternative large-area process or a process under atmospheric or reduced pressures is required. Thus, in this present study, we tried to synthesize such UV luminous hBN by a thermal chemical vapor phase deposition (CVD) under reduced pressures, and obtained the results as follow:
1. We have successfully synthesized hBN which exhibits intense UV light emission at 215 nm at room temperature in cathodoluminescence (CL) measurements on polycrystalline Ni substrates. The deposition temperature of 1170 degree C is lower by several hundreds of degree C than those used for the conventional hBN processes. The results of Raman measurements show crystallinity of the hBN is comparable to that of a HPHT single crystal hBN.
2. The formation of UV luminous hBN was accompanied by non-uniform lateral luminescence and surface roughening, which probably resulted from etching reaction between BCL_3 and Ni substrates at the high temperature.
3. We tried a new method which involved low-temperature deposition for suppression of the etching reaction and post-annealing at high temperatures for the improvement in crystallinity. The UV luminous hBN with a smoother surface was successfully formed by this method. The exciton luminescence was observed from spots with the size of a few μm, which were uniformly scattered in the 10×10mm^2 specimen. These results indicate that this method provides a way for the improvement in uniformity of luminescence. Although the mechanism is not clear, dissolution and precipitation of hBN at the interface are probably related to this phenomenon.
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