| Project/Area Number |
13650017
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Tokyo Metropolitan University |
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Principal Investigator |
OKUMURA Tsugunori Tokyo Metropolitan University, Professor, 工学研究科, 教授 (00117699)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Seiji Tokyo Metropolitan University, Research Associate, 工学研究科, 助手 (70336519)
SUHARA Michihiko Tokyo Metropolitan University, Associate Professor, 工学研究科, 助教授 (80251635)
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| Project Period (FY) |
2001 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2002: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2001: ¥3,100,000 (Direct Cost: ¥3,100,000)
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| Keywords | GaN / isothermal capacitance transient spectroscopy / photocapacitance spectroscopy / III-nitride semiconductors / schottky diode / impurity levels / ショットキーダイトード / GaN / DLTS / PHCAP / ICTS / PPC / YB |
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| Research Abstract |
III-nitride semiconductors have attracted much attention as promising materials for applications to short wavelength light-emitting devices, high temperature and high power and high frequency devices because of their superior properties, such as wide direct bandgap, high breakdown voltage, high electron saturation velocity, high thermal conductivity and high thermal stability. Despite the remarkable progress in crystal growth technique for III-nitride semiconductors, the doping and the deep-level defects in III-nitride semiconductors are still not fully understood. It is important to understand the origin and role of native defects and impurities in III-nitride semiconductors, because these point defects directly influence on device performance. The objective of this work is to characterize the correlation between optical and electrical properties of the deep-level defects in III-nitride semiconductors and to discuss their origins.
In this work, we have built the high-temperature capacitance transient spectroscopy system in order to characterize the deeper levels near the mid gap in GaN. We have also characterized the deep levels in the MOCVD-grown GaN layers by the developed measurement system. The increase in the photocapacitance was observed in both GaN samples in the range of 2.0 to 2.5 eV. This is due to the photoionization of carriers from the deep levels associated with the yellow luminescence (YL). In addition, the transient capacitance measurements after the photoionization were also performed in the range of 1.8 to 3.4 eV. The notable transient of capacitance was observed at the photon energies of about 2.1 eV and 3.4, which are correspond to the deep levels associated with YL and bandgap energy of GaN at room temperature, respectively. By using the isothermal capacitance transient spectroscopy (ICTS) analysis, it is noted that the deep trap levels is the minority carrier trap, because of the negative ICTS signals.
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