2006 Fiscal Year Final Research Report Summary
Development of InGaN quantum well photorefractive devices sensitive in blue region of spectrum
| Project/Area Number |
16360026
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Applied optics/Quantum optical engineering
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
KURODA Kazuo The University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (10107394)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ARAKAWA Yasuhiko The University of Tokyo, Research Center for Advanced Science and Technology, Professor, 先端科学技術研究センター, 教授 (30134638)
SHIMURA Tsutomu The University of Tokyo, Institute of Industrial Science, Professor, 生産技術研究所, 教授 (90196543)
ASHIHARA Satoshi Tokyo University of Agriculture and Technology, Department of Applied Physics, Accociate Professor, 共生科学技術研究院, 特任准教授 (10302621)
FUJIMURA Ryushi The University of Tokyo, Institute of Industrial Science, Associate Researcher, 生産技術研究所, 助教 (50361647)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Keywords | photorefractive device / InGaN quantum well / GaN thin laver / He ion illumination / EO modulator / photo carrier screening / uv argon ion laser |
|---|
| Research Abstract |
After recent quick development of GaN semiconductor lasers, the blue region of spectrum around 400 nm has attracted great attention in optical information technologies. The purpose of this research is to develop semiconductor photorefractive devices using InGaN quantum well structures sensitive in the blue region of spectrum.
(1) It is well known that there is a strong electric field inside the InGaN double hetero-junction structures because of large lattice constant mismatch. If we screen this internal field by creating photo-carriers at trap layers, we can control the transmittance of InGaN layers. Following this idea, we have fabricated optically-addressed spatial light modulators. By implanting high energy He ions, we have successfully improved the response speed and the spatial resolution.
In order to apply the external electric field perpendicular to the InGaN layers, we have developed the laser liftoff technology of InGaN layers from sapphire substrate. Optical modulation properties are substantially improved by the application of external field.
We have also employed pump-prove spectroscopy using the femtosecond laser pulses. We found that the relaxation rate on excited carrier is accelerated by the external field. These measurements gave us clear insight on optical and electric phenomena in the InGaN layers.
(2) We have conducted the investigation on the photorefractive effects in semi-insulating GaN thin layers and Fe-doped GaN crystals. We successfully detected the photorefractive effects in these materials at the wavelengths of 363.8, 405, and 458 nm. We measured two-wave-coupling gain coefficients and time constants. These results are the first observation on the photorefractive effects in GaN in the world.
|
