1994 Fiscal Year Final Research Report Summary
Optical Properties of Si Ultrafine Particles and the Applications to Light-Emitting Devices
| Project/Area Number |
04452172
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
電子材料工学
|
|---|
| Research Institution | The University of Electro-Communications |
|---|
Principal Investigator |
MORISAKI Hiroshi The University of Electro-Communications, Department of Electro-Communications, Professor, 電気通信学部, 教授 (00029167)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
ONO Hiroshi The University of Electro-Communications, Department of Electro-Communications,, 電気通信学部, 助手 (00134867)
|
|---|
| Project Period (FY) |
1992 – 1994
|
| Keywords | Visible Light Emission / Gas Evaporation Method / Porous Si / Temerature Dependence of Emission lntensity / Quantum Size Effect / Surface / lnterface of Fine Particles / 人工原子 |
|---|
| Research Abstract |
1. Visuble light emission from various types of Si nanostructures
(1) Si-doped SiO_2 glass : The Si-doped glass prepared by the sputtering method showed strong red luminescence after the heattreatment. The decay time-constant of pulsed EL was typecally about 0.4msec indicating that the recombination process is rather slow.
(2) Si ultrafine particles : The ultrafine particles prepared in hydrogen showed strong visible light PL without making oxidation procedure. EL was also observed from the same particles sandwiched by a Si substrate and an ITO glass.
(3) Oxygen-containing Si nanostructres : Si nanostructures composed of chained ultrafine particles prepared by the gas evaporation in oxygen-containing atmospohere showed strong blue light emission. The chemical composition of these structures were found to be SiO_X.
(4) Porous Si : The Si nanostructure within the porous Si was actually composed of Si ultrafine particles with nm size. The emission intensity from the porous Si at the room temperature increased about four orders of magnitude by changing the anodization temperature from 0ﾟC to 40ﾟC.The luminescence intensity becomes almost the same level at about 200K independent upon the anodization temperature, indicating that the emission is controlled by the nonradiative recombination velocity and not by the density of the emission centers.
2. Emission mechanisms
Red-to-yellow emissions from various types of Si nanostructures are most likely due to the same origin because of the quite similar temperature dependence of the emission intensity. Although the absorption process of the excitation light is likely to be related to the blue shift of the absorption edge associated with the quantum size effect, the emission comes from the emission centers located near the surface/interface of Si ultrafine particles.
The blue light emission was found to be related to the oxygen-deficient states within SiO_X.
|
