研究経歴 - 梅津　郁朗

pulsed laser melting

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研究期間： 2008年3月  -  現在

Effects of inter dot coupling in quantum dot ensemble

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研究期間： 2005年4月  -  現在

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Quantum confinement effect in single quantum dot is is well known. Although, interdot coupling in quantum dot ensemble is not well known. We investigate effect of inter dot coupling through optical and transport measurements.

Nanocrystal/polymer composite material

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研究期間： 2000年4月  -  2007年3月

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Novel colloidal CdS quantum dot, CdS quantum dot possessing PEG tethered chains (PEG-TC) on the surface, was prepared by Prof.Nagasaki in Tsukuba University. New type of quantum dot ensemble is possible by linking inorganic quantum dots using organic PEG-TC. A dye molecule was combined to CdS quantum dot thorough PEG-TC and energy transfer from quantum dot to dye molecule was measured by time resolved photoluminescence. We estimated energy transfer rate and found that it is relatively high due to the large spectral overlap between defect PL emission band of CdS and absorption band of dye molecule.

Pulsed laser deposition

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研究期間： 1995年4月  -  現在

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Pulsed laser deposition in inert background gas is known as a potential technique to prepare nanocrystals. We found that surface hydrogenated silicon nanocrystal can be prepared by using hydrogen gas instead of inert gas. The surface of nanocrystal is stabilized by hydrogenation and the aggregation is reduced. The size of the primary structure is not sensitive to the background gas pressure, while the secondary structure depends on the background gas pressure. The secondary structure shows fractal structure and the fractal dimension of the secondary structure can be controlled by background gas pressure. We are interested in the correlation between fractal structure and optical and electronic properties.

Nanoscale silicon

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研究期間： 1995年4月  -  現在

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Quantum confinement effects are thought to be most important for the properties of Si nanocrystal. Although, studies of other effects such as surface and aggregation effects are very important for deep understandind of the nature of Si nanocrystal. The surface defects formed during the natural oxidation act as photoluminescence properties. We found correlation between surface defects and PL centers. Optical absorption also depends on the surface condition. We further pointed out that surface structure affects the aggregation mechanism. The optical bandgap energy and the electronic transport depend on the aggregated secondary structure. The electric transport of this aggregated material shows hopping conduction. We found that this hopping conduction has correlation with the fractal dimension of aggregated nanocrystal. These results indicate that the control of aggregated structure is a possible technique to modify macroscopic properties of nanocrystal-film.

Amorphous silicon

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研究期間： 1988年4月  -  2000年3月

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Amorphous silicon is important for photovoltaic and TFT materials. We fabricated hydrogenated amorphous silicon films by conventional magnetron sputtering method. The films prepared by this method have efficient photoluminescence intensity.