Browsing by Author "Uraoka, Yukiharu"

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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
Nonvolatile Flash Memory Based on Biologically Integrated Hierarchical Nanostructures
(2013-10-08)
Sano, Ken-Ichi
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Miura, Atsushi
;
Yoshii, Shigeo
;
Okuda, Mitsuhiro
;
Fukuta, Megumi
The first six peptides of multifunctional titanium binding peptide-1 bestowed recombinant L-ferritin, minT1-LF, was genetically engineered and used to fabricate multilayered nanoparticle architecture. The multifunctionality of minT1-LF enables specific binding of nanoparticle-accommodated minT1-LF to the silicon substrate surface and wet biochemical fabrication of gate oxide layer by its biomineralization activity. Three-dimensional (3D) nanoparticle architecture with multilayered structure was fabricated by the biological layer-by-layer method and embedded in a metal oxide-semiconductor device structure as a charge storage node of a flash memory device. The 3D-integrated multilayered nanoparticle architecture successfully worked as a charge storage node in flash memory devices that exhibited improved charge storage capacity compared with that of a conventional monolayer structure device.
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
The characterization of a single discrete bionanodot for memory device applications
(2009-03-25)
Miura, Atsushi
;
Tanaka, Ryota
;
Uraoka, Yukiharu
;
Matsukawa, Nozomu
;
Yamashita, Ichiro
We investigated electronic properties of a biochemically synthesized cobalt oxide bionanodot (Co-BND) by means of scanning tunneling microscopy/spectroscopy (STM/STS) and Kelvin-probe force microscopy (KFM). Experimentally obtained I-V characteristics and numerically obtained dI/dV and (dI/dV)/(I/V) from I-V revealed the band gap energy, band position of valence and conduction band of the Co-BND. KFM observation shows that bias polarity dependent surface potential change after charge injection. The observed surface potential change indicates that the Co-BND has a charge storage capability. We demonstrated the application of Co-BNDs for electronic devices by choosing flash memory as the example device. The fabricated Co-BND embedded MOS memory showed clear memory operation due to the charge confinement in the embedded Co-BNDs.