| Project/Area Number |
11650009
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Applied materials science/Crystal engineering
|
|---|
| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
|---|
Principal Investigator |
HARA Kazuhiko TOKYO INSTITUTE OF TECHNOLOGY, GRADUATE SCHOOL OF SCIENCE AND ENGINEERING, ASSOCIATE PROFESSOR, 大学院・理工学研究科, 助教授 (80202266)
|
|---|
| Project Period (FY) |
1999 – 2000
|
| Project Status |
Completed (Fiscal Year 2000)
|
| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥3,100,000 (Direct Cost: ¥3,100,000)
|
|---|
| Keywords | GALLIUM NITRIDE / GALLIUM INDIUM NITRIDE / POWDER / PHOSPHOR / VAPOR PHASE SYNTHESIS / PHOTOLUMINESCENCE / X-RAY DIFFRACTION / X線回折 |
|---|
| Research Abstract |
(1) GaN crystalline powders were synthesized by the reaction of a Ga vapor with an ammonia gas at the reaction temperature T_r=900-1100℃ in an atmospheric-pressure open-tube reactor. The mean size of the GaN particles increased as T_r is raised. The powder synthesized at 900℃ consists of particles of various polyhedra, most of which have size of 0.2-0.4 μm. As T_r is raised, the particles tend to become larger. The size distribution also becomes much spread and reaches 0.3〜2.0 μm for T_r=1100℃.
(2) It was found by X-ray diffraction that the powders consist primarily of hexagonal GaN particles for T_r【greater than or equal】1050℃, whereas those synthesized at T_r【less than or equal】1000℃ contain cubic GaN (c-GaN) particles. The fractions of c-GaN in the powders determined based on theoretical calculations ware about 7 and 23% for the samples synthesized at 1000 and 900℃, respectively.
(3) The GaN powders exhibited photoluminescence (PL) dominated by the band edge emissions. The integrated PL intensity at 293 K is about 3 % of that obtained at 24 K for the GaN powders synthesized at higher T_r, indicating a low concentration of non-radiative centers. Thermal quenching is relatively significant for the powders synthesized at lower T_r. This is presumably due to enhanced non-radiative recombination at the surface because of their smaller particle size.
(4) Ga_<1-x>In_xN alloy powders were synthesized after installing a crucible for indium. The indium content, χ, of 0.04 was obtained for the sample synthesized at 800℃. χ decreased with raising T_r ; no indium was incorporated when T_r=1100℃. The sample with χ=0.02, which was synthesized at 1000℃, showed more intense PL than that synthesized at 1100℃, suggesting that carrier localization phenomena induced by the alloy fluctuation effectively suppress non-radiative recombination at the surface.
|
