Browsing by Author "Tojo, Yosuke"

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Controlled Reduction of Bionanodots for Better Charge Storage Characteristics of Bionanodots Flash Memory
(2009-04-01)
Tojo, Yosuke
;
Miura, Atsushi
;
Uraoka, Yukiharu
;
Fuyuki, Takashi
;
Yamashita, Ichiro
We proposed a new process technology, named the "bio-nano-process", in which semiconductor processing technology and biotechnology are conbined. We utilized a ferritin protein cobalt core as a memory node, and succeeded in performing the operation of floating gate memory. In this study, we undertook the reduction control of a cobalt core embedded in silicon oxide by thermal annealing. We also fabricated metal-oxide-semiconductor (MOS) capacitors with using the cobalt core and evaluated their electronic properties. As a result, we could elucidate the contribution of the metallic cobalt in the core by controlling of the ambient and temperature. We found that memory windows become large with increasing contribution of metallic cobalt. (C) 2009 The Japan Society of Applied Physics
Polycrystalline silicon thin-film transistor utilizing self-assembled monolayer for crystallization
(2013-07-01)
Tojo, Yosuke
;
Miura, Atsushi
;
Ishikawa, Yasuaki
;
Yamashita, Ichiro
;
Uraoka, Yukiharu
Crystallization employing an N-(2-aminoethyl)-3-aminopropyltrimethoxysilane self-assembled monolayer (AEAPS-SAM) to coordinate Ni metal catalyst was found to produce large grain poly-Si. A small concentration of Ni could be deposited controllably onto an AEAPS-SAM covered with Si by immersing it in Ni solution for 1-60 min. Larger grains and a lower Ni concentration in the poly-Si could be obtained by shorter immersion. Immersion for 1 min produced grains, as large as 47 mu m and a Ni concentration as low as 7.4 x 10(18) atoms/cm(3). A poly-Si thin-film transistor fabricated with AEAPS-SAMpoly-Si of 1 min immersion had a field-effect mobility of 98 cm(2)/(V s), which is one order of magnitude higher than that of a thin-film transistor fabricated without the AEAPS-SAM treatment. (C) 2013 Elsevier B. V. All rights reserved.
Positional Control of Crystal Grains in Silicon Thin Film Utilizing Cage-Shaped Protein
(2011-04-01)
Tojo, Yosuke
;
Miura, Atsushi
;
Yamashita, Ichiro
;
Uraoka, Yukiharu
;
交大名義發表
We have proposed a new crystallization method for silicon thin films utilizing a cage-shaped protein (ferritin), called "bio-nano crystallization", which combines semiconductor processing technology and biotechnology. We utilized nickel nanoparticle-accommodated ferritins as metal catalysts, and succeeded in performing the crystallization. When the ferritin was adsorbed randomly onto the film, crystal nuclei were formed at random places, thus grain position was randomly distributed. In this study, we performed the positional controlled deposition of ferritin by electrostatic interaction for location control of crystal grains. Positively charged areas were formed on negatively charged SiO(2) using 3-amino-propyltriethoxysilane (APTES) as the electrostatic pattern. As a result, we could optimize Ni ferritin concentration to make a large adsorption difference between APTES and amorphous silicon. Therefore, nickel nanoparticles adsorption areas were controlled using APTES patterns. Furthermore, the location control of crystallized areas was achieved by optimizing the concentration of Ni ferritin and the APTES pattern. (C) 2011 The Japan Society of Applied Physics