UENO Keiji

J-GLOBAL         Last updated: Apr 1, 2019 at 14:56
 
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Name
UENO Keiji
Affiliation
Saitama University
Section
Graduate School of Science and Engineering
Job title
Associate Professor

Research Areas

 
 

Academic & Professional Experience

 
Apr 2007
 - 
Today
Associate Professor, Graduate School of Science and Engineering, Saitama University
 
Oct 2002
 - 
Mar 2007
Associate Professor, Department of Chemistry, Faculty of Science, Saitama University
 
Apr 1990
 - 
Sep 2002
Research Associate, Department of Chemistry, Faculty of Science, The University of Tokyo
 

Published Papers

 
He Junyang, Fang Nan, Nakamura Keigo, Ueno Keiji, Taniguchi Takashi, Watanabe Kenji, Nagashio Kosuke
ADVANCED ELECTRONIC MATERIALS   4(7)    Jul 2018   [Refereed]
Nakata Yuki, Sugawara Katsuaki, Ichinokura Satoru, Okada Yoshinori, Hitosugi Taro, Koretsune Takashi, Ueno Keiji, Hasegawa Shuji, Takahashi Takashi, Sato Takafumi
NPJ 2D MATERIALS AND APPLICATIONS   2    May 2018   [Refereed]
Yamada Keiko, Souma Seigo, Yamauchi Kunihiko, Shimamura Natsumi, Sugawara Katsuaki, Trang Chi Xuan, Oguchi Tamio, Ueno Keiji, Takahashi Takashi, Sato Takafumi
NANO LETTERS   18(5) 3235-3240   May 2018   [Refereed]
Chang Yuan-Ming, Yang Shih-Hsien, Lin Che-Yi, Chen Chang-Hung, Lien Chen-Hsin, Jian Wen-Bin, Ueno Keiji, Suen Yuen-Wuu, Tsukagoshi Kazuhito, Lin Yen-Fu
ADVANCED MATERIALS   30(13)    Mar 2018   [Refereed]
Yamasaki Yuji, Moriya Rai, Arai Miho, Masubuchi Satoru, Pyon Sunseng, Tamegai Tsuyoshi, Ueno Keiji, Machida Tomoki
2D MATERIALS   4(4)    Dec 2017   [Refereed]
Jaker Hossain, Koji Kasahara, Daisuke Harada, A. T. M. Saiful Islam, Ryo Ishikawa, Keiji Ueno, Tatsuro Hanajiri, Yoshikata Nakajima, Yasuhiko Fujii, Masahide Tokuda, Hajime Shirai
Journal of Applied Physics   122(5) 055101   Aug 2017   [Refereed]
Zhou Lin, Huang Shengxi, Tatsumi Yuki, Wu Lijun, Guo Huaihong, Bie Ya-Qing, Ueno Keiji, Yang Teng, Zhu Yimei, Kong Jing, Saito Riichiro f, Dresselhaus Mildred
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   139(25) 8396-8399   Jun 2017   [Refereed]
Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Chemistry Letters   46 612-615   Jan 2017
© 2017 The Chemical Society of Japan.We have investigated the fabrication process of organic-inorganic perovskite {CH(NH2)2}1-xCsxPbI3 thin films on compact TiO2 layers by the reaction of porous PbCsxI2+x layers and CH(NH2)2I solution. The perovsk...
Jaker Hossain, Qiming Liu, Takuya Miura, Koji Kasahara, Daisuke Harada, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
ACS Applied Materials and Interfaces   8 31926-31934   Nov 2016
© 2016 American Chemical Society.We demonstrate the chemistry of amphiphilic perfluorosulfonic copolymer Nafion-coated conductive poly(3,4-ethyelenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and its effect on the photovoltaic performance o...
Lin Zhou, Ahmad Zubair, Ziqiang Wang, Xu Zhang, Fangping Ouyang, Fangping Ouyang, Kai Xu, Wenjing Fang, Keiji Ueno, Ju Li, Ju Li, Tomás Palacios, Jing Kong, Mildred S. Dresselhaus, Mildred S. Dresselhaus
Advanced Materials   28 9526-9531   Nov 2016
Takanori Yamanaka, Kenta Masumori, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Journal of Physical Chemistry C   120 25371-25377   Nov 2016
© 2016 American Chemical Society.Spectroscopic ellipsometry (SE) was used to investigate the role of isopropyl alcohol (IPA) solvent in the synthesis of organic-lead-halide perovskite CH(NH2)2PbIxBr3-x [FAPbIxBr3-x] thin films by the two-step reac...
Yuki Nakata, Katsuaki Sugawara, Ryota Shimizu, Ryota Shimizu, Yoshinori Okada, Patrick Han, Taro Hitosugi, Taro Hitosugi, Keiji Ueno, Takafumi Sato, Takashi Takahashi, Takashi Takahashi
NPG Asia Materials   8    Nov 2016
© 2016 The Author(s).The emergence of exotic quantum phenomena is often triggered by a subtle change in the crystal phase. Transition metal dichalcogenides (TMDs) exhibit a wide variety of novel properties, depending on their crystal phases, which...
Shuji Funda, Tatsuya Ohki, Qiming Liu, Jaker Hossain, Yoshihiro Ishimaru, Keiji Ueno, Hajime Shirai
Journal of Applied Physics   120    Jul 2016
© 2016 Author(s).We investigated the relationship between the fine structure of spin-coated conductive polymer poly(3,4-ethylenedioxythiphene):poly(styrene sulfonate) (PEDOT:PSS) films and the photovoltaic performance of PEDOT:PSS crystalline-Si (...
Tatsuya Ohki, Koki Ichikawa, Jaker Hossain, Yasuhiko Fujii, Tatsuro Hanajiri, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (A) Applications and Materials Science   213 1922-1925   Jul 2016
© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimWe investigated the chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on textured crystalline silicon (c-Si) substrate for efficient c-Si/PEDOT:P...
Shu Nakaharai, Mahito Yamamoto, Keiji Ueno, Kazuhito Tsukagoshi
ACS Applied Materials and Interfaces   8 14732-14739   Jun 2016
© 2016 American Chemical Society.The polarity of the charge carriers injected through Schottky junctions of α-phase molybdenum ditelluride (α-MoTe2) and various metals was characterized. We found that the Fermi-level pinning in the metal/α-MoTe2 S...
Mahito Yamamoto, Shu Nakaharai, Keiji Ueno, Kazuhito Tsukagoshi
Nano Letters   16 2720-2727   Apr 2016
© 2016 American Chemical Society.Transition metal oxides show much promise as effective p-type contacts and dopants in electronics based on transition metal dichalcogenides. Here we report that atomically thin films of under-stoichiometric tungste...
Jaker Hossain, Tatsuya Ohki, Koki Ichikawa, Kazuhiko Fujiyama, Keiji Ueno, Yasuhiko Fujii, Tatsuro Hanajiri, Hajime Shirai
Japanese Journal of Applied Physics   55    Mar 2016
© 2016 The Japan Society of Applied Physics.Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated in terms of cavitation frequency f, solvent, flow rate of nitrogen, substrate tempe...
Tomoki Machida, Tomoki Machida, Rai Moriya, Miho Aral, Yohta Sata, Takehiro Yamaguchi, Naoto Yabuki, Sei Morikawa, Satoru Masubuchi, Keiji Ueno
Technical Digest - International Electron Devices Meeting, IEDM   2016-February    Feb 2016
© 2015 IEEE.We fabricated van der Waals (vdW) junctions of two-dimensional (2D) crystals using mechanical exfoliation and transfer technique of atomic layers. By connecting cleaved flakes of Fe0.25TaS2, van der Waals magnet tunnel junction was con...
Ramesh Devkota, Qiming Liu, Tatsuya Ohki, Jaker Hossain, Keiji Ueno, Hajime Shirai
Applied Physics Express   9    Feb 2016
© 2016 The Japan Society of Applied Physics.Crystalline silicon double-heterojunction solar cells were fabricated using Si/organic and Si/Cs2CO3 heterojunctions. The front heterojunction is formed by spin-coating conductive polymer poly(3,4-ethyen...
Keiji Ueno
Journal of the Physical Society of Japan   84    Dec 2015
© 2015 The Physical Society of Japan.Semiconducting two-dimensional transition-metal dichalcogenides (MX2) are attracting much attention as promising materials for a new generation of optical and electronic devices. MX2 compounds are complementary...
Yen Fu Lin, Yong Xu, Che Yi Lin, Yuen Wuu Suen, Mahito Yamamoto, Shu Nakaharai, Keiji Ueno, Kazuhito Tsukagoshi
Advanced Materials   27 6612-6619   Nov 2015
© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Low-frequency current fluctuations are monitored and the mechanism of electric noise investigated in layered 2H-type α-molybdenum ditelluride transistors. The charge transport mechanism of electric...
Lin Zhou, Kai Xu, Kai Xu, Ahmad Zubair, Albert D. Liao, Wenjing Fang, Fangping Ouyang, Fangping Ouyang, Yi Hsien Lee, Keiji Ueno, Riichiro Saito, Tomás Palacios, Jing Kong, Mildred S. Dresselhaus, Mildred S. Dresselhaus
Journal of the American Chemical Society   137 11892-11895   Sep 2015
© 2015 American Chemical Society.The controlled synthesis of large-area, atomically thin molybdenum ditelluride (MoTe<inf>2</inf>) crystals is crucial for its various applications based on the attractive properties of this emerging material. In th...
Miho Arai, Rai Moriya, Naoto Yabuki, Satoru Masubuchi, Keiji Ueno, Tomoki Machida, Tomoki Machida
Applied Physics Letters   107    Sep 2015
© 2015 AIP Publishing LLC.We investigate the micromechanical exfoliation and van der Waals (vdW) assembly of ferromagnetic layered dichalcogenide Fe<inf>0.25</inf>TaS<inf>2</inf>. The vdW interlayer coupling at the Fe-intercalated plane of Fe<inf>...
Shu Nakaharai, Mahito Yamamoto, Keiji Ueno, Yen Fu Lin, Yen Fu Lin, Song Lin Li, Kazuhito Tsukagoshi
ACS Nano   9 5976-5983   Jun 2015
© 2015 American Chemical Society.A doping-free transistor made of ambipolar α-phase molybdenum ditelluride (α-MoTe<inf>2</inf>) is proposed in which the transistor polarity (p-type and n-type) is electrostatically controlled by dual top gates. The...
Huaihong Guo, Teng Yang, Teng Yang, Mahito Yamamoto, Lin Zhou, Ryo Ishikawa, Keiji Ueno, Kazuhito Tsukagoshi, Zhidong Zhang, Mildred S. Dresselhaus, Mildred S. Dresselhaus, Riichiro Saito
Physical Review B - Condensed Matter and Materials Physics   91    May 2015
© 2015 American Physical Society.We study the second-order Raman process of mono- and few-layer MoTe2, by combining ab initio density functional perturbation calculations with experimental Raman spectroscopy using 532, 633, and 785 nm excitation l...
Mahito Yamamoto, Sudipta Dutta, Sudipta Dutta, Shinya Aikawa, Shinya Aikawa, Shu Nakaharai, Katsunori Wakabayashi, Michael S. Fuhrer, Michael S. Fuhrer, Keiji Ueno, Kazuhito Tsukagoshi
Nano Letters   15 2067-2073   Mar 2015
© 2015 American Chemical Society.Growth of a uniform oxide film with a tunable thickness on two-dimensional transition metal dichalcogenides is of great importance for electronic and optoelectronic applications. Here we demonstrate homogeneous sur...
Koichi Suganuma, Hajime Shirai, Keiji Ueno
IEEJ Transactions on Electronics, Information and Systems   135 156-159   Feb 2015
© 2015 The Institute of Electrical Engineers of Japan.Complementary metal-oxide-semiconductor (CMOS) inverter circuits were fabricated using solution-processed field-effect transistors (FETs); p-type FET of 6,13-bis(triisopropylsilylethynyl)pentac...
Keiji Ueno, Koji Fukushima
Applied Physics Express   8    Jan 2015
© 2015 The Japan Society of Applied Physics.Molybdenum ditelluride (MoTe<inf>2</inf>) is known to have two different crystal phases: α-MoTe<inf>2</inf> and β-MoTe<inf>2</inf>. α-MoTe<inf>2</inf> is the polytype stable below 815 °C, and β-MoTe<inf>...
Qiming Liu, Ryo Ishikawa, Shuji Funada, Tatsuya Ohki, Keiji Ueno, Hajime Shirai
Advanced Energy Materials   5    Jan 2015
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.p-Toluenesulfonic acid/dimethyl sulfoxide (PTSA/DMSO)-treated poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/crystalline-silicon (c-Si) hybrid solar cells with a solution-proce...
Qiming Liu, Tatsuya Ohki, Dequan Liu, Hiromitsu Sugawara, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Nano Energy   11 260-266   Jan 2015
© 2014 Elsevier Ltd.We firstly investigated efficient poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS)/n-type polycrystalline silicon (p-Si) heterojunction solar cells fabricated by chemical mist deposition (CMD) using a hi...
Taiga Hiate, Naoto Miyauchi, Zeguo Tang, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   12 1191-1191   Jan 2015
© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.The above article, published online on 25 July 2015 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement be...
Yen Fu Lin, Yen Fu Lin, Yong Xu, Sheng Tsung Wang, Song Lin Li, Mahito Yamamoto, Alex Aparecido-Ferreira, Wenwu Li, Huabin Sun, Shu Nakaharai, Wen Bin Jian, Keiji Ueno, Kazuhito Tsukagoshi
Advanced Materials   26 3263-3269   May 2014
We report ambipolar charge transport in α-molybdenum ditelluride (MoTe2) flakes, whereby the temperature dependence of the electrical characteristics was systematically analyzed. The ambipolarity of the charge transport originated from the formati...
Ishwor Khatri, Ayo Hoshino, Fumiya Watanabe, Qiming Liu, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Thin Solid Films   558 306-310   May 2014
We prepare transparent, self-assembled polygonal silver nanowire (AgNW) mesh by bubble template and transferred as top electrode in poly(3,4- ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS)/n-silicon hybrid solar cell, which shows power...
Mahito Yamamoto, Sheng Tsung Wang, Meiyan Ni, Meiyan Ni, Yen Fu Lin, Yen Fu Lin, Song Lin Li, Shinya Aikawa, Wen Bin Jian, Keiji Ueno, Katsunori Wakabayashi, Kazuhito Tsukagoshi
ACS Nano   8 3895-3903   Apr 2014
Two-dimensional layered crystals could show phonon properties that are markedly distinct from those of their bulk counterparts, because of the loss of periodicities along the c-axis directions. Here we investigate the phonon properties of bulk and...
T. Hiate, N. Miyauchi, Q. Liu, R. Ishikawa, K. Ueno, H. Shirai
Journal of Applied Physics   115    Mar 2014
Real-time monitoring of optical anisotropy during growth by the chemical mist deposition of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films was carried out using spectroscopic ellipsometry. The microstructure of the grown...
I. Khatri, Z. Tang, T. Hiate, Q. Liu, R. Ishikawa, K. Ueno, H. Shirai
Journal of Applied Physics   116    Jan 2014
Ishwor Khatri, Qiming Liu, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   53    Jan 2014
© 2014 The Japan Society of Applied Physics.We report an enhancement in the efficiency of poly(3,4-ethylenedioxythiophene):poly(stylene sulfonate) (PEDOT:PSS)/n-Si hybrid solar cell by incorporating silver nanoparticles (AgNPs) with PEDOT:PSS. AgN...
Hajime Shirai, Keiji Ueno
Journal of the Institute of Electronics, Information and Communication Engineers   97 215-221   Jan 2014
Ishwor Khatri, Qiming Liu, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Canadian Journal of Physics   92 867-870   Jan 2014
We prepare transparent, selfassembled polygonal silver nanowire (AgNW) mesh by bubble template and use as top electrode for a poly (3, 4ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS)/n-Si hybrid solar cell. Devices were fabricated by p...
Ishwor Khatri, Qiming Liu, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Canadian Journal of Physics   92 849-852   Jan 2014
In this work, multiwalled carbon nanotubes (MWCNTs) are separated and cut into short pipes using a green tea solution and embedded at interface of poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS)/n-Si hybrid solar cells. Devices...
I. Khatri, Z. Tang, T. Hiate, Q. Liu, R. Ishikawa, K. Ueno, H. Shirai
Journal of Applied Physics   114    Dec 2013
We investigated the graphene oxide (GO) based n-type crystalline silicon (c-Si)/conductive poly(ethylene dioxythiophene):poly(styrenesulfonate)(PEDOT: PSS) Schottky junction devices with optical characterization and carrier transport measurement t...
H. S. Song, H. S. Song, S. L. Li, L. Gao, Y. Xu, K. Ueno, J. Tang, Y. B. Cheng, Y. B. Cheng, K. Tsukagoshi
Nanoscale   5 9666-9670   Oct 2013
Two-dimensional (2D) layered semiconductors are very promising for post-silicon ultrathin channels and flexible electronics due to the remarkable dimensional and mechanical properties. Besides molybdenum disulfide (MoS 2), the first recognized 2D ...
Q. Liu, I. Khatri, R. Ishikawa, A. Fujimori, K. Ueno, K. Manabe, H. Nishino, H. Shirai
Applied Physics Letters   103    Oct 2013
The effect of inserting an ultrathin layer of ferroelectric (FE) poly(vinylidene fluoride-tetrafluoroethylene) P(VDF-TeFE) at the crystalline (c-)Si/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) interface of a c-Si/PEDOT:PSS...
Qiming Liu, Takashi Imamura, Taiga Hiate, Ishwor Khatri, Zeguo Tang, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Applied Physics Letters   102    Jun 2013
An investigation was carried out into the effect of uniaxial optical anisotropy in poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) on the photovoltaic performance of crystalline Si/PEDOT:PSS heterojunction solar cells fabri...
Q. Liu, I. Khatri, R. Ishikawa, K. Ueno, H. Shirai
Applied Physics Letters   102    May 2013
The effects of MoO3 molecular doping in poly(3,4- ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS) on the chemical structure and, in turn, on the carrier collection efficiency of c-Si/PEDOT:PSS heterojunction solar cells are demonstrated...
Ishwor Khatri, Zeguo Tang, Qiming Liu, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Applied Physics Letters   102    Feb 2013
Poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS)/n-Si hybrid solar cells were studied with and without embedding green-tea modify multiwalled carbon nanotubes (MWCNTs) at interface. Devices fabricated with embedding green-tea mo...
Mayuko Kishi, Yosuke Kubo, Ryo Ishikawa, Hajime Shirai, Keiji Ueno
Japanese Journal of Applied Physics   52    Feb 2013
MoO3 is one of the efficient hole-transporting materials for organic photovoltaic cells (OPVs). Here, a facile method of preparing the MoO3 buffer layer will be introduced. MoO3 powder was added into methanol and ultrasonication of the dispersion ...
Ryo Ishikawa, Hajime Shirai, Keiji Ueno
Applied Physics Express   5    Dec 2012
The performance of an organic thin film photovoltaic cell was improved using a solution-processed fluorinated surfactant Zonyl FS-300 (Zonyl) cathode interlayer. Poly[N-90-heptadecanyl-2,7-carbazole-alt-5,5-(40,70-di-2-thienyl-20, 10,30-benzothiad...
Koichi Suganuma, Takuy Gotou, Keiji Ueno
Applied Physics Express   5    Dec 2012
Top-contacted organic field-effect transistors (OFETs) with graphene electrodes were fabricated by the laminate transfer method. Graphene electrodes were prepared on a different glass substrate and transferred onto an organic semiconductor layer o...
Keiji Ueno
Proceedings of the 19th International Workshop on Active-Matrix Flatpanel Displays and Devices - TFT Technologies and FPD Materials, AM-FPD 2012   49-52   Oct 2012
This article introduces the method to fabricate a transparent graphene conductive film from graphite powder by a solution process. Chemically oxidized graphite powder was dispersed in water, and it was exfoliated by repeated centrifugation and was...
Zeguo Tang, Qiming Liu, Ishwor Khatri, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   9 2075-2078   Oct 2012
We investigated the crystalline silicon (c-Si)/conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS):graphene oxide (GO) composite heterojunction devices with optical characterization and carrier transport measurement techni...
Taiga Hiate, Naoto Miyauchi, Zeguo Tang, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   9 2071-2074   Oct 2012
The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) and conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) on P3HT for use in crystalline silicon/organic hybrid heterojunction solar cells on CZ crystalli...
Taiga Hiate, Tomohisa Ino, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   51    Oct 2012
Electrospray-deposited poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated using several solvent solutions as a hole-transporting layer for spin-coated poly(3-hexylthiophene-2,5-diyl):[6,6]- phenyl-C61 butyric aci...
Qiming Liu, Fumiya Wanatabe, Aya Hoshino, Ryo Ishikawa, Takuya Gotou, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   51    Oct 2012
Soluble graphene oxide (GO) and plasma-reduced (pr-) GO were investigated using crystalline silicon (c-Si) (100)/GO/pr-GO hybrid junction solar cells. Their photovoltaic performances were compared with those of c-Si/GO/pristine conductive poly(eth...
Qiming Liu, Ishwor Khatri, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   9 2101-2106   Oct 2012
Efficient crystalline silicon (c-Si) heterojunction solar cells with conductive poly(ethylene dioxythiophene):poly(styrene sulfonate)(PEDOT:PSS) and graphene oxide (GO) are demonstrated using device structures of c-Si/GO/PEDOT:PSS/Ag and c-Si/PEDO...
Ishwor Khatri, Takashi Imamura, Akira Uehara, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   9 2134-2137   Oct 2012
The chemical mist deposition of graphene oxide (GO) and poly(3,4-ethylenedioxythiophene):poly(stylenesulfonate) (PEDOT:PSS) were investigated on the crystalline silicon (c-Si) substrate for the n-type c-Si/organic heterojunction solar cells. The u...
Tomohisa Ino, Taiga Hiate, Takeshi Fukuda, Keiji Ueno, Hajime Shirai
Journal of Non-Crystalline Solids   358 2520-2524   Sep 2012
The initial growth stage of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films by the electrospray deposition (ESD) method was investigated using 70% N,N-dimethylformamide (DMF) as a solvent solution through the real-time s...
Yoko Takeyama, Shingo Maruyama, Hiroki Taniguchi, Mitsuru Itoh, Keiji Ueno, Yuji Matsumoto
CrystEngComm   14 4939-4945   Aug 2012
Ionic liquid-mediated vacuum deposition was demonstrated as a novel growth technique for high-quality C 60 crystallites. In this process the ionic liquid worked as a solvent, i.e. the gas phase C 60 precursors were continuously fed into the ionic ...
Tomohisa Ino, Masahiro Ono, Naoto Miyauchi, Qiming Liu, Zeguo Tang, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   51    Jun 2012
The electrospray deposition (ESD) of poly(3-hexylthiophene) (P3HT) films for use in crystalline silicon/organic hybrid heterojunction solar cells on a crystalline silicon (c-Si) wafer was investigated using real-time characterization by spectrosco...
Qiming Liu, Masahiro Ono, Zeguo Tang, Ryo Ishikawa, Keiji Ueno, Hajime Shirai
Applied Physics Letters   100    Apr 2012
We demonstrate a highly efficient hybrid crystalline silicon (c-Si) based photovoltaic devices with hole-transporting transparent conductive poly-(3,4-ethlenedioxythiophene):poly(styrenesufonic acid) (PEDOT:PSS) films, incorporating a Zonyl fluoro...
Masahiro Ono, Zeguo Tang, Ryo Ishikawa, Takuya Gotou, Keiji Ueno, Hajime Shirai
Applied Physics Express   5    Mar 2012
Efficient crystalline silicon (c-Si) heterojunction solar cells with conductive poly(ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and graphene oxide (GO) composite are demonstrated using a structure of Ag/PEDOT:PSS/PEDOT:PSS:GO com...
Tomohisa Ino, Tatsuya Hayashi, Takeshi Fukuda, Keiji Ueno, Hajime Shirai
Physica Status Solidi (C) Current Topics in Solid State Physics   8 3025-3028   Oct 2011
Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated poly(3,4-ethylene-dioxythiophene):(polystyrene sulfonic acid) (PEDOT:PSS) films were investigated by real-time spectroscopic ellipsometry (SE) characteri...
Tomohisa Ino, Takashi Asano, Takeshi Fukuda, Keiji Ueno, Hajime Shirai
Journal of Nanoscience and Nanotechnology   11 8030-8034   Sep 2011
Kinetic spectroscopic ellipsometry have been used to study the initial growth stage of poly(3,4- polyethylene dioxythiophene):poly(styrenesulfonic acid)(PEDOT:PSS) films by the electrospray deposition (ESD) method. The real-time spectra analysis r...
Tomohisa Ino, Tatsuya Hayashi, Takeshi Fukuda, Keiji Ueno, Hajime Shirai
Journal of Nanoscience and Nanotechnology   11 8035-8039   Sep 2011
Highly-conductive poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films obtained by the addition of dimethylsulfoxide (DMSO) and the argon plasma exposure were used as a transparent conductive anode (TCA) for copper-phtha...
Tomohisa Ino, Tatsuya Hayashi, Keiji Ueno, Hajime Shirai
Thin Solid Films   519 6834-6839   Aug 2011
Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated 3,4-polyethylenedioxythiophene:polystyrenesulfonic acid (PEDOT:PSS) films were investigated by real-time characterization by the spectroscopic ellipsomet...
Tomohisa Ino, Takashi Asano, Takeshi Fukuda, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   50    Aug 2011
Kinetic spectroscopic ellipsometry has been used to study the initial growth stage of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films by the electrospray deposition (ESD) method. The real-time spectra analysis revea...
Tomohisa Ino, Tatsuya Hayashi, Keiji Ueno, Hajime Shirai
Japanese Journal of Applied Physics   50    Aug 2011
Depth profiles of the optical constants, carrier mobility, and carrier density of spin-coated poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films were investigated by real-time characterization by spectroscopic ellipsome...
Shogo Kato, Ryo Ishikawa, Yosuke Kubo, Hajime Shirai, Keiji Ueno
Japanese Journal of Applied Physics   50    Jul 2011
We introduce a new method to fabricate a MoO3 hole-transporting layer for organic photovoltaic cells (OPVs). We fabricated a MoS2 film from its solution and converted it to MoO3. MoS2 has a lamellar crystal structure similar to graphite, and it ca...
Takeshi Fukuda, Takeshi Fukuda, Kenji Takagi, Kenji Takagi, Takashi Asano, Takashi Asano, Zentaro Honda, Norihiko Kamata, Keiji Ueno, Hajime Shirai, Jungmyoung Ju, Yutaka Yamagata, Yusuke Tajima
Physica Status Solidi - Rapid Research Letters   5 229-231   Jul 2011
A high-efficiency bulk heterojunction organic photovoltaic cell (OPV) was achieved by the electrospray deposition method. The surface roughness of the P3HT:PCBM thin film can be reduced using the mixed solvent consisting of o-dichlorobenzene (o-DC...
Koichi Suganuma, Shunichiro Watanabe, Takuya Gotou, Keiji Ueno
Applied Physics Express   4    Feb 2011
Transparent organic field-effect transistors with solution-processed graphene source-drain and gate electrodes were fabricated on flexible substrates. Graphene electrodes were formulated by chemical and thermal reduction of solution-processed grap...
Satoko Takebayashi, Shigeomi Abe, Koichiro Saiki, Keiji Ueno
Applied Physics Letters   94    Mar 2009
Pentacene field-effect transistors (FETs) were fabricated on a poly(vinyl alcohol) (PVA)-coated Ta2 O5 gate dielectric using Au source/drain electrodes. Their device characteristics were examined before and after annealing the FETs in a vacuum. Be...
Toshihiro Shimada, Yui Ishii, Keiji Ueno, Tetsuya Hasegawa
Journal of Crystal Growth   311 163-166   Dec 2008
We studied the effect of the substrate materials on the solution-mediated vacuum deposition of organic semiconductor rubrene using liquid flux with a low vapor pressure. We found that bis-2-ethylhexyl phthalate was suitable as the liquid flux. It ...
Toshihiro Shimada;Manabu Ohtomo;Tadamasa Suzuki;Tetsuya Hasegawa;Keiji Ueno;Susumu Ikeda;Koichiro Saiki;Miho Sasaki;Katsuhiko Inaba
APPLIED PHYSICS LETTERS   93(22) 223303   Dec 2008
We developed a nanoscale orientation template for quasisingle crystalline epitaxial growth of thin film phase pentacene. By using α- √3×√3 Bi termination of surface dangling bonds on step-bunched vicinal surface of Si(111), thin film phase epitaxi...
Ryo Onoki;Genki Yoshikawa;Yuki Tsuruma;Susumu Ikeda;Koichiro Saiki;Keiji Ueno
Langmuir   24(20) 11605-11610   Oct 2008
A poly(3-dodecylthiophene-2,5-diyl) film having in-plane anisotropic molecular arrangement was successfully fabricated by transferring its Langmuir-Blodgett film onto a step-bunched Si(111) substrate. Polarized near-edge X-ray absorption fine stru...
Seiichiro Yaginuma;Kenji Itaka;Masamitsu Haemori;Masao Katayama;Keiji Ueno;Tsuyoshi Ohnishi;Mikk Lippmaa;Yuji Matsumoto;Hideomi Koinuma
APPLIED PHYSICS EXPRESS   1(1) 015005-1-015005-3   Jan 2008
The observation of reflection high energy electron diffraction (RHEED) oscillations has been proved to be a key to open the nano-world of materials, since it definitely verifies that the film growth proceeds in layer-by-layer mode with each layer ...
斉木幸一朗,上野啓司
JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS   46(36-40) L913-L916   Oct 2007
The mobility of pentacene-based organic field-effect transistors (OFETs) fabricated on natural mica substrates has been highly improved using poly (methyl methacrylate) (PMMA) or octadecyltrimethoxysillane (OTMS) as a buffer layer between the mica...
Tadamasa Suzuki, Toshihiro Shimada, Keiji Ueno, Susumu Ikeda, Koichiro Saiki, Tetsuya Hasegawa
Materials Research Society Symposium Proceedings   965 380-385   Dec 2006
Ryo Onoki, Shigeomi Abe, Keiji Ueno, Hiroo Nakahara, Koichiro Saiki
Chemistry Letters   35 746-747   Jul 2006
We fabricated an ordered monolayer film of a long-chain fatty acid or a perfluorofatty acid onto an anodized tantalum oxide (Ta 2O 5) amorphous surface by the Langmuir-Blodgett (LB) method, and grew a pentacene or C 60 thin film on it. Remarkable ...
Ryo Onoki, Keiji Ueno, Hiroo Nakahara, Genki Yoshikawa, Susumu Ikeda, Shiro Entani, Tetsuhiko Miyadera, Ikuyo Nakai, Hiroshi Kondoh, Toshiaki Ohta, Manabu Kiguchi, Koichiro Saiki, Koichiro Saiki
Langmuir   22 5742-5747   Jun 2006
Alternating facet/terrace nanostructures were fabricated on a SiO 2 surface by step-bunching and thermal oxidation of a vicinal Si(111) substrate, and their influence upon the polymerization direction of a long-chain diacetylene derivative monolay...
G. Yoshikawa, T. Miyader, R. Onoki, K. Ueno, I. Nakai, S. Entani, S. Ikeda, D. Guo, M. Kiguchi, H. Kondoh,T. Ohta and K. Saiki
SURFACE SCIENCE   600(12) 2518-2522   Jun 2006
Molecular orientations of pentacene ultrathin films grown on SiO2 substrates were studied without the influence of the atmosphere by vacuum atomic force microscopy (V-AFM) and near edge X-ray absorption fine structure (NEXAFS). The experimental pr...
Akira Matsumoto, Ryo Onoki, Keiji Ueno, Susumu Ikeda, Koichiro Saiki
Chemistry Letters   35 354-355   Apr 2006
We fabricated pentacene-based organic field-effect transistors (OFETs) using single-crystalline natural mica substrates as the gate dielectric. Substrate temperatures during the deposition of pentacene films were varied from room temperature (RT) ...
上野啓司,斉木幸一朗
JOURNAL OF APPLIED PHYSICS   98(11) 114503-1-114503-5   Dec 2005
Electrolytically polished surfaces of Ta sheets were anodized in an aqueous KI solution to form Ta2 O5 films with a relatively high dielectric constant and a high breakdown electric field. Organic field-effect transistors (OFETs) were fabricated o...
Shimada T, Nogawa H, Hasegawa T, Okada R, Ichikawa H, Ueno K, Saiki K
APPLIED PHYSICS LETTERS   87(6) 061917   Sep 2005
The epitaxial growth of pentacene on hydrogen-terminated Si(111) is reported. Reflection high energy electron diffraction (RHEED) revealed that the crystal packing resembles that in the bulk crystal even at a monolayer thickness, which was maintai...
Okada R, Miyadera T, Shimada T, Koma A, Ueno K, Saiki K
Surface Science   552(1/3) 46-52   Mar 2004
Methyl-terminated Si(1 1 1) (Me-Si(1 1 1)) and bilayer-GaSe terminated Si (BGS) surfaces were investigated to explore their usefulness as the protection layer in the fabrication process of nanometer-scale self-assembled monolayers (SAMs). BGS was ...
Masao Katayama, Keiji Ueno, Atsushi Koma, Manabu Kiguchi, Koichiro Saiki
JAPANESE JOURNAL OF APPLIED PHYSICS   43(2A) L203-L205   Feb 2004
LiBr/Si(001) heterostructure has been investigated by scanning tunneling microscopy and spectroscopy (STM and STS). In the initial stage of LiBr growth, rectangular islands are observed consisting of accumulation of about 0.2 nm-thick unit layers....
Manabu Kiguchi, Manabu Nakayama, Kohei Fujiwara, Keiji Ueno, Toshihiro Shimada, Koichiro Saiki, Koichiro Saiki
JAPANESE JOURNAL OF APPLIED PHYSICS   42(12A) L1408-L1410   Dec 2003
We present a simple but powerful method to determine the thicknesses of the accumulation and depletion layers and the distribution curve of injected carriers in organic field effect transistors. The conductivity of organic semiconductors in thin f...
Genki Yoshikawa, Manabu Kiguchi, Keiji Ueno, Atsushi Koma, Koichiro Saiki, Koichiro Saiki
Surface Science   544(2/3) 220-226   Oct 2003
CsCl has been known to show extraordinary photoemission by visible (VIS) light only after ultraviolet (UV) light irradiation. To elucidate this phenomenon, photo yield and photoemission spectrum of a single-crystalline CsCl thin film were measured...
上野啓司,斉木幸一朗,小間篤
Surface Science Sp. Iss. SI   514(1-3) 27-32   Aug 2002
Nano-scale oxide patterns were fabricated on a bilayer-GaSe terminated Si(1 1 1) surface using an atomic force microscope (AFM) in air. The Si(1 1 1) surface regularly terminated by bilayer-GaSe is very stable in air, although it can be oxidized t...
上野啓司,斉木幸一朗,小間篤
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   40(3B) 1888-1891   Dec 2001
We have developed a novel method to fabricate self-assembled quantum dots (QDs) of compound semiconductors on a Si(111) substrate using the so-called 'droplet epitaxy' technique. In order to fabricate QDs on a Si substrate by droplet epitaxy, we e...
上野啓司,斉木幸一朗,小間篤
APPLIED SURFACE SCIENCE   169-170 184-187   Jan 2001
We have investigated the electronic structure of KxC60 (x = 0-6) using low-energy electron energy loss spectroscopy (LEELS), especially focusing on the K3p core-electron excitation spectra. It is found that the structure of the K3p-excitation spec...
Toshiyuki Hayashi, Keiji Ueno, Koichiro Saiki, Atsushi Koma
Journal of Crystal Growth   219 115-122   Oct 2000
Sub-monolayer films of layered semiconductor InSe were grown on MoS, substrates by molecular beam epitaxy, and the change in their growth features with Se/In flux ratio was investigated using scanning tunneling microscope in vacuum. It was found t...
斉木幸一朗上野啓司,小間篤
REVIEW OF SCIENTIFIC INSTRUMENTS   71(9) 3478-3479   Sep 2000
Micro-channel plate (MCP) was used to intensify the image on the fluorescent screen in reflection high-energy electron diffraction. The primary electron current could be reduced by four orders of magnitude to get the image of the same intensity as...
上野啓司,斉木幸一朗,小間篤
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW   38(1B) 511-514   Dec 1999
We propose a new method to fabricate nano-scale devices consisting of C60. C60 molecules have a spherical shape with a diameter of 0.7 nm. It may be possible to consider each molecule as a quantum dot to fabricate a single-electron-tunneling devic...
上野啓司小間篤
APPLIED SURFACE SCIENCE   130-132 670-675   Jun 1998
C60 molecules were deposited on a submonolayer InSe film which was grown on a MoS2 substrate. In the previous experiment on the growth of a C60 thin film on a Se/MoS2 heterostructure, C60 grew only on exposed MoS2 regions and never nucleated on Ga...
上野啓司,小間篤
JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   36(6B) 4061-4064   Jun 1997
A novel method of fabricating organic material nanostructures using selective growth on patterned layered material surfaces has been developed. First, an epitaxial monolayer film of layered semiconductor GaSe was grown on a cleaved face of MoS2. T...
Keiji Ueno, Natsuko Takeda, Kentaro Sasaki, Atsushi Koma
Applied Surface Science   113-114 38-42   Apr 1997
Heteroepitaxial films of lamellar semiconductor GaSe were grown on MoS2 cleaved surfaces by molecular beam epitaxy, and its growth mechanism was investigated by atomic force microscope. At the initial stage of the growth, triangular islands of GaS...
上野啓司,斉木幸一朗,小間篤
APPLIED PHYSICS LETTERS   70(9) 1104-1106   Mar 1997
Nanostructures consisting of C60 molecules were fabricated on a GaSeTMoS2 heterostructure. A submonolayer film of a lamellar compound semiconductor GaSe was grown on a MoS2 substrate to form nanoscale holes or grooves surrounded by monolayer steps...
Hiroyuki Yamada, Keiji Ueno, Atsushi Koma
Japanese Journal of Applied Physics, Part 2: Letters   35    May 1996
Layered semiconductor GaS thin films have been grown by molecular beam epitaxy on hydrogen-terminated Si(111) and GaSe(0001) substrates. Elemental sulfur is so volatile that we used a valved cell as a sulfur source. Twoapprox.100 monolayer of GaS ...
Hideki Abe, Kotaro Kataoka, Keiji Ueno, Atsushi Koma
Japanese Journal of Applied Physics   34 3342   Jun 1995
Two metal elements, Sn and Na, have been deposited onto layered semiconductor MoS2(0001) surfaces and observed with a scanning tunneling microscope. The metal-adsorbed area shows a very large dark spot (3-5nm diameter) when the sample bias is posi...

Misc

 
上野啓司,小間篤
JOURNAL OF APPLIED PHYSICS   68(5) 2168-2175   1990
上野啓司,小間篤
APPLIED PHYSICS LETTERS   58(5) 472-474   1991
表面を選ぶサッカーボール
上野啓司
物理科学雑誌パリティ   13(11) 47-50   1998
上野啓司,小間篤,斉木幸一朗
PHYSICAL REVIEW B   62(12) 8281-8285   2000
上野啓司,斉木幸一朗,小間篤
JOURNAL OF CRYSTAL GROWTH   219(1/2) 115-122   2000
上野啓司,小間篤
JOURNAL OF APPLIED PHYSICS   90(1) 209-212   2001
上野啓司,小間篤
日本結晶成長学会誌   28(3) 164-173   2001
上野啓司,斉木幸一朗,小間篤
JOURNAL OF CRYSTAL GROWTH   237(2) 1610-1614   2002
上野啓司,斉木幸一朗,小間篤
APPLIED SURFACE SCIENCE   190(1/4) 485-490   2002
表面不活性化シリコン基板上における異方的有機薄膜成長
応用物理   28(3) 46-55   2003
表面不活性化シリコン基板上における異方的有機薄膜成長
上野啓司,斉木幸一朗小間篤
応用物理   72(3) 322-326   2003
Y. Yamamoto, H. Ichikawa, K. Ueno, A. Koma, K. Saiki, T. Shimada
PHYSICAL REVIEW B   70(15) 155415-1-155415-6   2004
高誘電率ゲート酸化膜を用いた電界効果トランジスタによる有機薄膜の物性変調
上野啓司
総合研究機構研究プロジェクト研究成果報告書   16年度    2005
溶液系の有機デバイス作製技術検討
上野啓司,小野木亮,高橋新,森朋彦
埼玉大学地域共同研究センター紀要   7 49-52   2006
層状化合物を用いた高移動度フレキシブル電界効果トランジスタの開発に関する研究
上野啓司
総合研究機構研究プロジェクト研究成果報告書   第4号(17年度)    2006
直鎖π共役電子系の電気伝導度測定に関する研究
上野啓司
総合研究機構研究プロジェクト研究成果報告書   第5号(18年度) 553-554   2007
低次元構造半導体を用いた新奇薄膜電界効果トランジスタ形成に関する研究
上野啓司,小野木亮,阿部重臣,松本晃,川端ちひろ,平岡和,保戸塚梢,白石淳子,高橋新,武林聡子,坪倉陽
科学研究費補助金(基盤研究(C)) 研究成果報告書   平成17-18年度 1-45   2007

Research Grants & Projects

 
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