2006 Fiscal Year Final Research Report Summary
Control of Anisotropy in Nanostructured Silicon by Linearly Polarized Light
| Project/Area Number |
16510087
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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 |
Nanomaterials/Nanobioscience
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| Research Institution | Hyogo University of Teacher Education |
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Principal Investigator |
KOYAMA Hideki Hyogo University of Teacher Education, Graduate School of Education, Associate Professor, 学校教育研究科, 助教授 (40234918)
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| Project Period (FY) |
2004 – 2006
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| Keywords | porous silicon / porous Si / photoluminescence / anodization / optical anisotropy / polarization / nanostructure |
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| Research Abstract |
Nanostructured porous silicon samples exhibit optical anisotropy after being irradiated with linearly polarized light while they are etched electrochemically. This research project aims at clarifying the mechanism for the formation of anisotropy and applying this to novel optical devices. Major results are summarized as follows:
1. Observation of anisotropy in refractive indices
The optical anisotropy in porous silicon layers has been reported by several research groups based on their results on the degree of linear polarization in photoluminescence. In this project, we have observed a significant anisotropy in refractive indices for the first time. The anisotropy is such that the largest index appears in a direction 90-degree off that of the largest degree of linear polarization. This can be explained by assuming that large silicon structures are responsible for refractive index anisotropy while small structures govern luminescence anisotropy.
2. Effect of excitation wavelengths on lumin
… More
escence anisotropy
We have observed that the luminescence anisotropy is affected largely by the excitation wavelength. Our experimental results show that this is not due to the effect of luminescence from oxides but is originating from depth inhomogeneity.
3. Experimental observation and computer simulation of the strong anisotropy in samples irradiated with infrared laser light
We have used a 1.06-μm Nd : YAG laser of relatively high intensity as an illumination source and obtained very strong luminescence anisotropy. The result can be reproduced well by computer simulation based on a two-dimensional model in which linear oscillators are distributed in a plane.
4. Effect of anodization conditions
We have shown that luminescent porous silicon samples can be obtained by using extremely dilute HF solutions with HF concentrations down to 0.1%. No significant luminescence anisotropy, however, has been observed in these samples, implying that anodization current density largely affects the formation of anisotropy. Less
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Research Products
(8 results)
