1998 Fiscal Year Final Research Report Summary
Fabrication of super sensitive ultraviolet photodetector
| Project/Area Number |
09450133
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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 | Meijo University |
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Principal Investigator |
AKASAKI Isamu Meijo University Fac.Sci.& Technol.Professor, 理工学部, 教授 (20144115)
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| Co-Investigator(Kenkyū-buntansha) |
AMANO Hiroshi Meijo University Fac.Sci.& Technol.Associate Professor, 理工学部, 助教授 (60202694)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Group III nitride / Widegap Semiconductor / Ultraviolet / Photodetector / pn-diode / Photo-cell |
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| Research Abstract |
In order to fabricate highly resistive undoped GaN, correlation between growth condition and electrical properties has been intensively studied. It is found that with increase of ammonia flow rate during growth, resistivity of undoped GaN become higher and higher. Highly pure undoped GaN with residual impurity concentration of less than 10^<14>cm^3 has been achieved.
New growth sequence has been established, by which threading dislocation density of GaN on sapphire has been reduced more than two orders of magnitude. This new method was also applied to grow AlGaN.Crack free and high quality AlGaN with a whole compositional range can be grown.
UV photo-cell was fabricated using undoped GaN grown by the new method. It showed photo-response even under the very weak illumination condition with a power of 100pW/cm^2. UV photo-cell based on undoped Al_<0.2>Ga_<0.8>N was also been fabricated. Cut off wavelength is 335 nm, and the sensitivity is 5A/W, which is the world's highest ever reported.
GaN based pn-junction diode was fabricated. Origin of the leakage current has been intensively studied. At low bias condition, surface leakage current through mesa is dominant, while at high bias condition, tunnel current is dominant. The new photodiode showed very low leakage current of 0.8pA.
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