| Project/Area Number |
18340092
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics I
|
|---|
| Research Institution | Sophia University |
|---|
Principal Investigator |
EMA Kazuhiro Sophia University, Physics, Professor (40194021)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
KUNUGITA Hideyuki Sophia university, Physics, Assistant Professor (50296886)
OHTSUKI Tomi Sophia university, Physics, Professor (50201976)
KIKUCHI Akihiko Sophia university, Physics, Lecturer (90266073)
|
|---|
| Project Period (FY) |
2006 – 2007
|
| Project Status |
Completed (Fiscal Year 2007)
|
| Budget Amount *help |
¥16,600,000 (Direct Cost: ¥14,800,000、Indirect Cost: ¥1,800,000)
Fiscal Year 2007: ¥7,800,000 (Direct Cost: ¥6,000,000、Indirect Cost: ¥1,800,000)
Fiscal Year 2006: ¥8,800,000 (Direct Cost: ¥8,800,000)
|
|---|
| Keywords | semiconductor / nanocolumn / GaN / exciton / polariton / quantum well / InGaN / biexciton / レーザー |
|---|
| Research Abstract |
The purpose of this project was to observe multi-quantum-well polariton coupling in GaN and InGaN/GaN nanocolumns. However we have not observed the polariton coupling, because quantum wells in the nanocolumns have different resonance energies. We have observed peculiar optical properties due to the nanocolumn morphology. We have studied specific optical properties of the GaN nanocolumn, focusing on the influence of the columnar shape.
In photoluminescence (PL) spectrum of GaN nanocolumns with large diameters (〜100nm) there are two peaks attributed to free A-excitons (A) and bound excitons (I). With decreasing the diameter, higher-energy peaks whose energy positions correspond to B-excitons (B) and C-excitons (C) appear. In order to elucidate the origin of this, we calculated PL spectra of GaN nanocolumns considering the polaritonic effect of the excitons; i.e. considering propagation and radiation from both the top and the side surfaces of the nanocolumns. The results show that the peaks of B and C excitons become remarkable with decreasing the diameter because PL from the side surface becomes important.
We also observed biexciton emissions in GaN nanocolumns with large diameters, and found that the biexciton binding energies are higher than that in bulk samples. Although the mechanism for the increase in the binding energy is not clear at the present, we suppose that it arises from spatial confinement effect due to the nanocolumn morphology.
|
