(Lecture, Nov 9) Simple Syntheses of Si-Based Nanowires, Nanosheets and their Bundle Structures
November 02,2017 11:24:05 readCount:67
Topic: Simple Syntheses of Si-Based Nanowires, Nanosheets and their Bundle Structures
Speaker: Prof. Hirokazu Tatsuoka(Shizuoka University)
Venue: Room 205, Building No.14, Wushan Campus
Time: Thursday, Nov 9, 2017, 10:00 - 11:30 
 
[Abstract]
Low-dimensional materials have attracted much interest because of their enhanced or modified optical, electronic and mechanical properties compared to those of bulk materials. A series of bottom-up shape modifications is shown for the syntheses of Si-based nanostructures. Round, hexagonal, square and triangular – faceted Si nanowires were synthesized by catalytic growth with MnCl2/Si powder source as shown in Fig.1, and the growth evolution of the faceted Si nanowires by vapor-liquid-solid (VLS) mechanism, followed by vapor-solid-solid (VSS) is discussed. A nanowire bundle or a nanosheet bundle is also one of important structures for technological applications. It has been demonstrated that Si-based nanowire and nanosheet bundles can be prepared. In this study, CrSi2, SiOx, Mg2Si/MgO composite, Mg2Si and MnSi1.7 nanowires and their bundles were successfully synthesized as shown in Fig.2. Si nanosheets connected to Si nanowires were also synthesized using MnCl2/Si source. In addition, the formation of free standing Si nanosheets by Ca extraction from CaSi2 by thermal treatment in metal-chloride vapor or aqueous inositol hexakisphosphate (IP6) solution is reported as shown in Fig.3.
 
In addition, the structural properties of the nanoproducts were examined. The structural control and morphological modifications of the nanowire and nanosheet bundles have been successfully demonstrated by the appropriate thermal or chemical treatments with specific starting materials. It is also expected that the simple and easy nanostructure fabrication technique will encourage us to develop new widely-used nanostructured materials and devices with a large volume and/or large area. Further characterization of the bundle structures will be expected to evaluate the enhanced electric, thermal and thermoelectric properties of the Si-based materials, and applications for use in sophisticated Si-based devices in the future.
1. Synthesis of flower-like Si nanostructures on Si substrates, Peiling Yuan, Ryo Tamaki, Hiroaki Suzuki, Kenta Sasaki, Makoto Nakayama, Yuya Saito, Shinya Kusazaki, Yuki Kumazawa, Xiang Meng, Nazmul Ahsan, Yoshitaka Okada and Hirokazu Tatsuoka, Jpn J.Appl.Phys., (2017)
2. Synthesis of crystalline Si-based nanosheets by extraction of Ca from CaSi2 in inositol hexakisphosphate solution, Xiang Meng, Kenta Sasaki, Koki Sano, Peiling Yuan, and Hirokazu Tatsuoka, Jpn J.Appl.Phys. (2017)
3. Ordered CaSi2 microwall arrays on Si substrates induced by the Kirkendall effect, Xiang Meng, Akiko Ueki, Hirokazu Tatsuoka, and Hiroshi Itahara, Chemistry - A European Journal, (2017)
4. Synthesis and structural property of Si nanosheets connected to Si nanowires using MnCl2/Si powder source, Erchao Meng, Akiko Ueki, Xiang Meng, Hiroaki Suzuki, Hiroshi Itahara, and Hirokazu Tatsuoka, Appl. Surf. Sci. 378, 460–466 (2016).
5. Synthesis and structural control of silicon and silicide nanowires/microrods using metal chloride sources, Hirokazu Tatsuoka, Hiroaki Suzuki, Takanori Suzuki, Wen Li, Junhua Hu, Xiang Meng, and Erchao Meng, Jpn J.Appl.Phys. 54, 07JD02 (2015) 
6. High power factor of Ga-doped compositionally homogeneous Si0.68Ge0.32 bulk crystal grown by the vertical temperature gradient freezing method, Omprakash, Muthusamy; Arivanandhan, Mukannan; Koyama, Tadanobu; Momose, Yoshimi; Ikeda, Hiroya; Tatsuoka, Hirokazu; Aswal, Dinesh; Bhattacharya, Shovit; Okano, Yasunori ; Ozawa, Tetsuo; Inatomi, Yuko; Moorthy Babu, Sridharan; Hayakawa, Yasuhiro, Crystal Growth & Design, 15(3), 1380-1388 (2015)
 
[Biography]
Professor Hirokazu Tatsuoka of Department of Electronics and Materials Science, Shizuoka University, received his Bachelor, Master and PhD degree of Engineering all at Shizuoka University. He is a specialist in the field of semiconductor engineering, science and technology of nano-materials, crystals and thin film surface physics. he used to work for Fujitsu Laboratory as a researcher, and working for amorphous materials. The main orientation of scientific activity, now, is an experimental study of growth and characterizations of nano-structures, films and bulk crystals of semiconducting silicides/oxides and their application for photovoltaic and thermoelectric devises. He leads the professional Group on Semiconducting Silicides and Related Materials of Japan Society of Applied Physics. He is also interested in international collaboration and exchange activities.
 

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