| Project/Area Number |
16H03857
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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 |
Crystal engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
花田 貴 東北大学, 金属材料研究所, 助教 (80211481)
谷川 智之 東北大学, 金属材料研究所, 講師 (90633537)
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| Project Period (FY) |
2016-04-01 – 2019-03-31
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| Project Status |
Completed (Fiscal Year 2018)
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| Budget Amount *help |
¥16,250,000 (Direct Cost: ¥12,500,000、Indirect Cost: ¥3,750,000)
Fiscal Year 2018: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
Fiscal Year 2017: ¥5,330,000 (Direct Cost: ¥4,100,000、Indirect Cost: ¥1,230,000)
Fiscal Year 2016: ¥5,590,000 (Direct Cost: ¥4,300,000、Indirect Cost: ¥1,290,000)
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| Keywords | 窒化物半導体 / 極性 / 有機金属気相成長 / 分極効果 / HEMT / 高電子移動度トランジスタ / GaN / 有機金属気相成長法 / N極性 / ヘテロ構造 |
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| Outline of Final Research Achievements |
In nitride semiconductors famous for blue LEDs, the author proposed in 2006 that the nitrogen-polar growth was effective for devices. The purpose of this research is to reduce both concentrations of carbon and oxygen, which are said to be highly incorporated during the epitaxial growth. Both concentrations of carbon and oxygen have been reduced by increasing the concentration of hydrogen in the carrier gas and the source supply ration of ammonia to Ga source, respectively. GaN/GaAlN/GaN inverted HEMT structure with a flat surface can be successfully grown by introducing a sapphire substrate with off angle of 0.8 deg. from c-plane. The characteristics of its two-dimensional electron gas was almost the same as a Ga-polar HEMT. This HEMT showed triode characteristics and the pinch-off operation. These results reveal that the growth technique developed here is effective for the fabrication of inverted HEMTs.
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| Academic Significance and Societal Importance of the Research Achievements |
窒化物半導体素子にはGa極成長が用いられている。窒化物半導体に存在する分極が素子特性を決定する。現状の携帯電話の基地局用高移動度電子トランジスタはGaAlN/GaN/基板の積層構造からなる。結晶極性にGa極性を用いているため、金属電極を広ギャップ半導体GaAlNに形成する必要があり、接触抵抗が大きくなり、現在より一桁周波数の高い次世代の携帯電話には対応できない。Ga極性と逆の窒素極性を用いると、層構造を反転でき、金属電極の接触抵抗を低減でき、高周波動作が可能となる。本研究の学術的意義としては、成長機構解明の発展と、インジウムを含む材料の組成域拡大である。これらの点の学術的意義は計り知れない。
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