1996 Fiscal Year Final Research Report Summary
Growth of GaN Using Microwave-Excited N Plasma Method
| Project/Area Number |
07805032
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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 |
Electronic materials/Electric materials
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| Research Institution | Yamaguchi Unversity |
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Principal Investigator |
KAI Ayako Yamaguchi University, Department of Electrical and Electronic Engineering, Lecturer, 工学部, 講師 (50253167)
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| Co-Investigator(Kenkyū-buntansha) |
TAGUCHI Tsunemasa Yamaguchi University, Department of Electrical and Electronic Engineering, Profe, 工学部, 教授 (90101279)
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| Project Period (FY) |
1995 – 1996
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| Keywords | GaN / Microwave-Excited Plasma Method / Plasma / Crystal Growth / Photoluminescence / Free exciton |
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| Research Abstract |
Hexagonal GaN films were grown in gallium and nitrogen plasmas excited by microwaves. When the microwave power was lower than 500 W, the emission spectra from the plasma were composed of atomic N,neutral N_2 molecule (the first positive and second positive series transitions) and N_2^+ ion (the first negative series). The intensity of the atomic N peaks increased at the microwave power higher than 500 W and new strong peaks due to atomic Ga appeared. When the atomic Ga peaks arose, GaN was grown, whereas the surface of the Ga metal was nitrided when the peaks were absent.
Although the resulting GaN films were composed of polycrystals, they showed strong peaks in the emission spectra near the band edge even at room temperature. The emission at 77 K and room temperature consisted of two components. One is attributable to the recombination of free excitons because the peak energy is almost equal to the free exciton energy. The other is ascribed to recombination related to localized states because the emission intensity saturates under high density excitation. The results of the time-resolved luminescence at 77 K and room temperature also revealed that the emission consists of two components, obeying a double-exponential decay. The first decay component is due to free exciton recombination and the slow one is ascribed to recombination of localized excitons. It is emphasized that the strong UV emission of free excitons is observable at room temperature.
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