1997 Fiscal Year Final Research Report Summary
Development and Application of Bule Light-Emitting Nanocrystalline Si Materials
| Project/Area Number |
08455152
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | The Institute of Physical and Chemical Research (RIKEN) |
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Principal Investigator |
AOYAGI Yoshinobu RIKEN,Semiconductor Laboratory, Chief Scientist, 半導体工学研究室, 主任研究員 (70087469)
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| Co-Investigator(Kenkyū-buntansha) |
HASUMI Masahiko Univ.of Agri.and Indust., Research Asistant, 工学部, 助手 (60261153)
NOMURA Shintaro RIKEN,Semiconductor Laboratory, Scientist, 半導体工学研究室, 研究員 (90271527)
ZHAO Xinwei RIKEN,Nanoelectronics Materials, Scientist, ナノ電子材料研究チーム, フロンティア研究員 (50260211)
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| Project Period (FY) |
1996 – 1997
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| Keywords | nanocrystalline Si / blue light emission / quantum size effect / Si quantum dot / direct transition / Er / all-Si laser / optical communication |
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| Research Abstract |
In Si nanostructures, quantum size effects are expected to give rise to new optical and electrical properties to replace present materials. The motivation of this study is to develop such new materials and new devices. Nanocrystalline Si (nc-Si) provides a way to fabricate Si into am scale. We have developed a successful process to fabricate nc-Si with controllable crystallite sizes and demonstrated a blue light emission from nc-Si at room temperature. Main results of this project are shown in bellow.
(1).Size-dependent blue light emission from nc-Si
Size control of Si nanocrystallites formed in a-Si matrix is achieved by using Er as a nucleation center. We have fabricated a series of nc-Si samples with size from 3 nm to 10 am. The smallest crystallite size was 2.7 nm, a Si dot including .-l000 atoms. The nc-Si layers are homogeneous both in the crystallite size and in the optoelectronic properties and show a blue emission band and a sharp peak at 1.54mum which is caused by intra-shell t
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ransitions in Er atoms up to room temperature. We showed that the blue emission shift to higher energies with decreasing size. The value of the shift is in good agreement with the absorption data and could be explained by a novel quantum size effect.
(2).First evidence of quantum size effect in ne-Si
By controlling the nanocrystallite size of nc-Si, we demonstrated that both the absorption and reflection spectra of nc-Si shift to higher energy side with decreasing crystallite size. The shift was well explained by the quantum size effect which originates direct transitions in the indirect semiconductor Si. The nc-Si is a promising material with size-tunable optical and electronic properties.
(3).A new model of nc-Si/a-Si quantum dot system
We proposed a new model of order (nc-Si phase)/disorder (a-Si phase) quantum dots system to understand the size effect of electrons in nc-Si materials. A theoretical calculation indicates that direct transitions enhanced by a modification of k-selection rules due to the size reduction result in the blue light emission, Both the absorption and reflection spectra calculated by the proposed model show size effect and are in good agreement with our experimental results.
(4).An Er-doped nc-Si laser operated at room temperature
We have fabricated Er-doped nc-Si waveguides on Si substrates and demonstrated a stimulated emission at 1.54 .tm at room temperature under optical pumping. This is the first breakthrough of realizing an all-Si laser. Less
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