研究者詳細 - 後藤　秀徳

論文 - 後藤　秀徳

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Observation of zero resistivity in K-doped picene 査読

Teranishi Kazuya, He Xuexia, Sakai Yusuke, Izumi Masanari, Goto Hidenori, Eguchi Ritsuko, Takabayashi Yasuhiro, Kambe Takashi, Kubozono Yoshihiro

PHYSICAL REVIEW B 87 ( 6 ) 06505 2013年2月

Observation of zero resistivity in K-doped picene 査読

Kazuya Teranishi, Xuexia He, Yusuke Sakai, Masanari Izumi, Hidenori Goto, Ritsuko Eguchi, Yasuhiro Takabayashi, Takashi Kambe, Yoshihiro Kubozono

PHYSICAL REVIEW B 87 ( 6 ) 2013年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

We report the observation of zero resistivity (rho) in a hydrocarbon superconductor, and describe the temperature dependence of rho in metal-doped hydrocarbons. The resistivity of K-doped picene (K(x)picene) has been recorded from pellet samples in a four-terminal measurement mode. A drop in rho is observed below 7 K for K(3.1)picene and below 11 K for K(3.5)picene, which clearly displays zero resistivity. The resistivity drop at 7 K is consistent with the superconducting critical temperature (T-c) obtained from the magnetic susceptibility of the 7 K phase of K(3)picene, while the drop at 11 K is inconsistent with the T-c's of both the 7 and 18 K phases of K(3)picene reported previously. The temperature dependence of rho for both samples exhibits granular-metal-like behavior in the normal state. DOI: 10.1103/PhysRevB.87.060505

DOI： 10.1103/PhysRevB.87.060505

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Phenanthro[1,2-b: 8,7-b '] dithiophene: a new picene-type molecule for transistor applications 査読

Yasushi Nishihara, Megumi Kinoshita, Keita Hyodo, Yasuhiro Okuda, Ritsuko Eguchi, Hidenori Goto, Shino Hamao, Yasuhiro Takabayashi, Yoshihiro Kubozono

RSC ADVANCES 3 ( 42 ) 19341 - 19347 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

A new picene-type molecule, phenanthro[1,2-b : 8,7-b'] dithiophene, has been synthesized for use in organic field-effect transistors (OFETs). The molecule consists of a phenanthrene core with two thiophene rings fused on the ends. This molecule can be recognized as a picene analogue. The electronic structure of the molecule was determined by its optical absorption spectrum together with a theoretical calculation based on density functional theory (DFT). The topological and electronic structures of thin films produced by direct thermal evaporation of the compounds and by deposition from a solution were characterized by optical imaging, X-ray diffraction, and atomic force microscopy. FET devices were fabricated with these thin films, and showed field-effect mobility as high as 10(-1) cm(2) V-1 s(-1).

DOI： 10.1039/c3ra44050h

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Fabrication of high performance/highly functional field-effect transistor devices based on [6]phenacene thin films 査読

Ritsuko Eguchi, Xuexia He, Shino Hamao, Hidenori Goto, Hideki Okamoto, Shin Gohda, Kaori Sato, Yoshihiro Kubozono

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 15 ( 47 ) 20611 - 20617 2013年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ROYAL SOC CHEMISTRY

Field-effect transistors (FETs) based on [6]phenacene thin films were fabricated with SiO2 and parylene gate dielectrics. These FET devices exhibit field-effect mobility in the saturation regime as high as 7.4 cm(2) V-1 s(-1), which is one of the highest reported values for organic thin-film FETs. The two- and four-probe mobilities in the linear regime display nearly similar values, suggesting negligible contact resistance at 300 K. FET characteristics were investigated using two-probe and four-probe measurement modes at 50-300 K. The two-probe mobility of the saturation regime can be explained by the multiple shallow trap and release model, while the intrinsic mobility obtained by the four-probe measurement in the linear regime is better explained by the phenomenon of transport with charge carrier scattering at low temperatures. The FET device fabricated with a parylene gate dielectric on polyethylene terephthalate possesses both transparency and flexibility, implying feasibility of practical application of [6] phenacene FETs in flexible/transparent electronics. N-channel FET characteristics were also achieved in the [6] phenacene thin-film FETs using metals that possess a small work function for use as source/drain electrodes.

DOI： 10.1039/c3cp53598c

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Electric-double-layer transistors with thin crystals of FeSe_1-xTe_x (x = 0.9 and 1.0) 査読

R. Eguchi, M. Senda, E. Uesugi, H. Goto, T. Kambe, T. Noji, Y. Koike, A. Fujiwara, Y. Kubozono

Appl. Phys. Lett. 102 103506-1 - 103506-4 2013年

Synthesis and physical properties of metal-doped picene solids 査読

Takashi Kambe, Xuexia He, Yosuke Takahashi, Yusuke Yamanari, Kazuya Teranishi, Hiroki Mitamura, Seiji Shibasaki, Keitaro Tomita, Ritsuko Eguchi, Hidenori Goto, Yasuhiro Takabayashi, Takashi Kato, Akihiko Fujiwara, Toshikaze Kariyado, Hideo Aoki, Yoshihiro Kubozono

PHYSICAL REVIEW B 86 ( 21 ) 2012年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER PHYSICAL SOC

We report electronic-structure and physical properties of metal-doped picene as well as selective synthesis of the phase that exhibits 18-K superconducting transition. First, Raman scattering is used to characterize the number of electrons transferred from the dopants to picene molecules, where a softening of Raman scattering peaks enables us to determine the number of transferred electrons. From this, we have identified that three electrons are transferred to each picene molecule in the superconducting doped picene solids. Second, we report pressure dependence of T-c in 7- and 18-K phases of K(3)picene. The 7-K phase shows a negative pressure dependence, while the 18-K phase exhibits a positive pressure dependence which can not be understood with a simple phonon mechanism of BCS superconductivity. Third, we report a synthesis method for superconducting K(3)picene by a solution process with monomethylamine CH3NH2. This method enables us to prepare selectively the K(3)picene sample exhibiting 18-K superconducting transition. The method for preparing K(3)picene with T-c = 18 K found here may facilitate clarification of the mechanism of superconductivity.

DOI： 10.1103/PhysRevB.86.214507

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O-2-exposure and light-irradiation properties of picene thin film field-effect transistor: A new way toward O-2 gas sensor 査読

Yasuyuki Sugawara, Keiko Ogawa, Hidenori Goto, Shuhei Oikawa, Kouki Akaike, Noriko Komura, Ritsuko Eguchi, Yumiko Kaji, Shin Gohda, Yoshihiro Kubozono

SENSORS AND ACTUATORS B-CHEMICAL 171 544 - 549 2012年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE SA

Transistor characteristics and O-2 gas sensing properties are investigated for picene thin film field-effect transistors (FETs) with ZrO2, Ta2O5, HfO2 and BaxSr1-xTiO3 (x = 0.4). The low-voltage operation is achieved using the above oxides with high gate dielectric constant, contrary to SiO2 gate dielectric. The O-2 gas sensing is achieved at 11 s intervals without any bias stress by an application of pulse drain and gate voltages (V-D and V-G), in contrast to previous result in which the O-2 gas sensing was performed at least at 1 h step because of bias stress effect. The actual O-2 sensing-speed in the picene thin film FET was similar to 10 s for 3.8 Torr O-2, and the O-2 sensing limit was concluded to be 0.15-0.38 Torr. Furthermore, it has been found that the O-2 sensing properties are observed only under irradiation of light with wavelength below 400 nm. From the result, we have presented two scenarios for O-2 sensing mechanism in picene thin film FET. (C) 2012 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.snb.2012.05.030

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Characteristics of [6]phenacene thin film field-effect transistor 査読

Noriko Komura, Hidenori Goto, Xuexia He, Hiroki Mitamura, Ritsuko Eguchi, Yumiko Kaji, Hideki Okamoto, Yasuyuki Sugawara, Shin Gohda, Kaori Sato, Yoshihiro Kubozono

APPLIED PHYSICS LETTERS 101 ( 8 ) 2012年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER INST PHYSICS

Transistor characteristics are studied for field-effect transistors (FETs) with thin films of [6]phenacene, which has six benzene rings and W-shape structure. The molecular alignment preferable for FET transport is found to be formed in [6]phenacene thin films. The transistor shows clear p-channel FET characteristics with field-effect mobility mu as high as 3.7 cm(2) V-1 s(-1). The similar O-2 sensing properties to picene FET are observed in [6]phenacene thin film FET. The bias stress properties are observed in [6]phenacene thin film FET. The pulse-voltage application suppresses the bias-stress effect and it enables a continuous O-2 sensing in [6]phenacene FET. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4747201]

DOI： 10.1063/1.4747201

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Characteristics of Single Crystal Field-Effect Transistors with a New Type of Aromatic Hydrocarbon, Picene 査読

Nobuyuki Kawai, Ritsuko Eguchi, Hidenori Goto, Kouki Akaike, Yumiko Kaji, Takashi Kambe, Akihiko Fujiwara, Yoshihiro Kubozono

JOURNAL OF PHYSICAL CHEMISTRY C 116 ( 14 ) 7983 - 7988 2012年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AMER CHEMICAL SOC

Picene is a phenacene-type aromatic hydrocarbon molecule with five benzene rings. We have fabricated picene single crystal (SC) field-effect transistors (FETs) with solid gate and ionic liquid gate dielectrics. Although the picene SC FET showed a large hole-injection barrier without any modification of interface between source/drain electrodes and picene SC, such a large hole-injection barrier could be effectively reduced by modifying the interface with tetracyanoquinodimethane (TCNQ). Picene SC FET with an HfO2 gate dielectric and TCNQ:coated electrodes shows p-channel characteristics with a smooth hole injection and a field-effect mobility more than 1 cm(2) V-1 s(-1) in two-terminal measurement. Picene SC FET could be operated even in bottom-contact structure by modifying the interface with octanethiol. Furthermore, picene SC FET operated with ionic liquid gate dielectric, [1-butyl-3-methylimidazolium][hexafluorophosphate], showing the field-effect mobility of 1.8 X 10(-1) cm(2) V-1 s(-1) and low absolute value, 1.9 V, of threshold voltage.

DOI： 10.1021/jp300052p

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Characteristics of conjugated hydrocarbon based thin film transistor with ionic liquid gate dielectric 査読

Yumiko Kaji, Keiko Ogawa, Ritsuko Eguchi, Hidenori Goto, Yasuyuki Sugawara, Takashi Kambe, Koki Akaike, Shin Gohda, Akihiko Fujiwara, Yoshihiro Kubozono

ORGANIC ELECTRONICS 12 ( 12 ) 2076 - 2083 2011年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：ELSEVIER SCIENCE BV

Thin film transistors (TFTs) with ionic liquid gate dielectrics, [1-ethyl-3-methylimidazolium][bis(trifluoromethanesulfonyl) imide] (emim[TFSI]) and [1-butyl-3-methylimidazolium][hexafluorophosphate] (bmim[PF6]), are fabricated with thin films of one dimensional (1D) hydrocarbon, [7]phenacene. P-channel characteristics are observed for [7] phenacene TFTs with both ionic liquids by use of platinum electrode. The field-effect mobility mu for [7]phenacene TFT with bmim[PF6] was recorded to be 0.28 cm(2) V-1 s(-1). The value of absolute threshold voltage, vertical bar V-TH vertical bar, was less than 2.5 V, showing low-voltage operation. The accumulation of hole in the [7]phenacene TFTs with ionic liquids was confirmed from the voltage or time dependence of capacitance in metal-insulator-semiconductor structure, which shows that these TFTs operate electrochemically and the carriers are accumulated in the whole of [7]phenacene thin films. (C) 2011 Elsevier B. V. All rights reserved.

DOI： 10.1016/j.orgel.2011.08.016

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Introducing Nonuniform Strain to Graphene Using Dielectric Nanopillars 査読

Hikari Tomori, Akinobu Kanda, Hidenori Goto, Youiti Ootuka, Kazuhito Tsukagoshi, Satoshi Moriyama, Eiichiro Watanabe, Daiju Tsuya

APPLIED PHYSICS EXPRESS 4 ( 7 ) 2011年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC APPLIED PHYSICS

A method for inducing nonuniform strain in graphene films is developed. Pillars made of a dielectric material (electron beam resist) are placed between graphene and the substrate, and graphene sections between pillars are attached to the substrate. The strength and spatial pattern of the strain can be controlled by the size and separation of the pillars. Application of strain is confirmed by Raman spectroscopy as well as from scanning electron microscopy (SEM) images. From SEM images, the maximum stretch of the graphene film reaches about 20%. This technique can be applied to the formation of band gaps in graphene. (C) 2011 The Japan Society of Applied Physics

DOI： 10.1143/APEX.4.075102

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Fabrication of ultrashort graphene Josephson junctions 査読

Tomori H, Kanda A, Goto H, Takana S, Ootuka Y, Tsukagoshi K

Physica C: Superconductivity 470 ( 20 ) 1492 - 1495 2010年

Effect of current annealing on electronic properties of multilayer graphene 査読

Tanaka S, Goto H, Tomori H, Ootuka Y, Tsukagoshi K, Kanda A

Journal of Physics: Conference Series 232 ( 1 ) 012015 2010年

Dependence of proximity-induced supercurrent on junction length in multilayer-graphene Josephson junctions 査読

Kanda A, Sato T, Goto H, Tomori H, Takana S, Ootuka Y, Tsukagoshi K

Physica C: Superconductivity 470 ( 20 ) 1477 - 1480 2010年

Inverse spin valve effect in multilayer graphene device 査読

Goto H, Tanaka S, Tomori H, Ootuka Y, Tsukagoshi K, Kanda A

Journal of Physics: Conference Series 232 ( 1 ) 012002 2010年

Inter-layer screening length to electric field in thin graphite film 査読

Hisao Miyazaki, Shunsuke Odaka, Takashi Sato, Sho Tanaka, Hidenori Goto, Akinobu Kanda, Kazuhito Tsukagoshi, Youiti Ootuka, Yoshinobu Aoyagi

APPLIED PHYSICS EXPRESS 1 ( 3 ) 2008年3月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC APPLIED PHYSICS

Electric conduction in thin graphite film was tuned by two gate electrodes to clarify how the gate electric field induces electric carriers in thin graphite. The graphite was sandwiched between two gate electrodes arranged in a top and bottom gate configuration. A scan of the top gate voltage generates a resistance peak in ambiploar response. The ambipolar peak is shifted by the bottom gate voltage, where the shift rate depends on the graphite thickness. The thickness-dependent peak shift was clarified in terms of the inter-layer screening length to the electric field in the double-gated graphite film. The screening length of 1.2 nm was experimentally obtained. (C) 2008 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.1.034007

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Coulomb blockade oscillations in narrow corrugated graphite ribbons 査読

Hisao Miyazaki, Shunsuke Odaka, Takashi Sato, Sho Tanaka, Hidenori Goto, Akinobu Kanda, Kazuhito Tsukagoshi, Youiti Ootuka, Yoshinobu Aoyagi

APPLIED PHYSICS EXPRESS 1 ( 2 ) 2008年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：JAPAN SOC APPLIED PHYSICS

We report Coulomb blockade oscillations in an atomically thin graphite ribbon fabricated by the micromechanical cleavage technique. Aperiodic current oscillations as a function of the gate voltage indicate the formation of multiple Coulomb islands inside the thin graphite ribbon. We conclude that the Coulomb islands originate from puddles of electrons and holes caused by the inhomogeneous interface between the ribbon and the substrate. (C) 2008 The Japan Society of Applied Physics.

DOI： 10.1143/APEX.1.024001

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A different type of reentrant behavior in superconductor/thin graphite film/superconductor Josephson junctions 査読

Sato T, Kanda A, Moriki T, Goto H, Tanaka S, Ootuka Y, Miyazaki H, Odaka S, Tsukagoshi K, Aoyagi Y

Physica C: Superconductivity and its applications 468 ( 7 ) 797 2008年

Gate-controlled superconducting proximity effect in ultrathin graphite films 査読

Sato T, Moriki T, Tanaka S, Kanda A, Goto H, Miyazaki H, Odaka S, Ootuka Y, Tsukagoshi K, Aoyagi Y

Physica E: Low-dimensional Systems and Nanostructures 40 ( 5 ) 1495 2008年

Observation of gate-controlled superconducting proximity effect in microfabricated thin graphite films 査読

Sato T, Kanda A, Tanaka S, Goto H, Ootuka Y, Miyazaki H, Odaka S, Tsukagoshi K, Aoyagi Y

Journal of Physics: Conference Series 109 ( 1 ) 012031 2008年

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