| Project/Area Number |
08455148
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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 |
Electronic materials/Electric materials
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| Research Institution | Yamaguchi University |
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Principal Investigator |
TAGUCHI Tsunemasa Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (90101279)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Yoichi Yamaguchi University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00251033)
SHINOZUKA Yuzo Yamaguchi University, Faculty of Engineering, Professor, 工学部, 教授 (30144918)
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| Project Period (FY) |
1996 – 1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥7,700,000 (Direct Cost: ¥7,700,000)
Fiscal Year 1997: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1996: ¥4,400,000 (Direct Cost: ¥4,400,000)
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| Keywords | nitride semiconductor / alloy semiconductor / moleclar beam epitaxy / exciton / localization / isoelectronic impurity / self trapping / stimulated emission / 誘導放出 / RF放電 / ドナー束縛励起子 / マイクロ波プラズマ / ラジカル源 |
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| Research Abstract |
We have studied the growth and the excitonic optical properties of nitride semiconductors, especially In _xGa_<1-x>N ternary alloys, in order to clarify the radiative recombination process responsible for high luminescence efficiency.
Photoluminescence measurement was performed for GaN epitaxial layrs grown under various conditions by RF-MBE.It was foudn that the sample grown under a Ga-rich condition showed an extremely strong excitonic luminescence line. Temperature dependence of the excitonic luminescence line revealed an abnormal behavior below 150 K.The abnormal linewidth broadening with temperature can not be explained by a typical model of exciton localization in an inhomogeneously-broadened system. We should consider another type of recombination process, such as exciton self-trapping or -capturing due to lattice distortion induced around defect sites.
In the case of an In_<0.08>Ga_<0.92>N ternary alloy epitaxial layr, the photoluminescence spectrum was dominated by an intense si
… More
ngle broad emission band with a peak energy and a linewidth of 384 nm and 38 meV,respectively, at low temperature. It was found from temperature-dependent and time-resolved photoluminescence measurements that the single broad emission band consisted of two components. Surface-mode stimulated emission was observed under high-density excitation at the energy position of the lower-energy component from low temperature up to room temperature. The origin of the lower-energy component was explained by considering an extrinsic exciton self-trapping due to In clusters in ternary alloys.
We have also observed that the intensity of near-UV luminescence from a Si-doped In_<0.08>Ga_<0.93>N layr with an electron concentration of 2 * 10^<18> cm^<-3> was approximately one order of magnitude stronger than that from an undoped one. It is reasonable to understand that the photogenerated carrier trapping by Si donors takes place effectively before the annihilation of carriers by nonradiative recombination processes. This fact unambiguously indicates that the doping of Si donors into active layrs has a large possibility to enhance the performance of light-emitting devices. Less
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