Evolutionary Shape Modification of Semiconductor Nanostructures

Abstract:
- Si, silicide, oxides, nanowires, microrods and nanosheets -
Shape control of nanostructures is an important issue because the physical properties of the nanostructures are dependent on their dimensions and shape. A series of bottom-up shape modifications by simple thermal treatment is shown for the syntheses of semiconductor nanostructures. The driving forces of the shape modifications are compared and discussed for (1) the round, hexagonal, square and triangular – faceted Si nanowires synthesized by catalytic growth with MnCl2/Si powder source, (2) wire – belt-like oxide nanostructures grown by the thermal oxidation of metallic sources. The growth evolution of the faceted Si nanowires by VLS followed by VSS mechanism is discussed. The Si nanostructure shape modification from the nanowires to nanosheets is also shown. In addition, the shape modification using a template technique from MoS2 to form h-MoSi2 nanosheets will be mentioned. Moreover, synthesis of Si-based nanosheet bundles by extraction of metallic atoms from CaSi2 by not only chloride vapor but also chelating agents is proposed. The detailed structural properties of the resulted nanostructures will be systematically shown.

Biography:
Professor Hirokazu Tatsuoka, is a specialist in the field of semiconductor engineering, science and technology of nano-materials, crystals and thin film surface physics. The main orientation of scientific activity 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 the Japan Society of Applied Physics(JSAP).