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SUMMARY:Electron Tunnelling through Rigid Molecular Wire Anchored between 
 Nanogap Electrodes and on Metal Surface (SP Workshop) - Mr Chun Ouyang\, M
 aterials and Structures Laboratory\, Tokyo Institute of Technology
DTSTART:20161019T131500Z
DTEND:20161019T141500Z
UID:TALK68694@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:The ultimate aim of molecular electronics is to develop and ma
 ster single molecule device. Prior to this\, it is important to understand
  the electron transport behavior through -conjugation system [1-3]. Mol
 ecular wires are one of candidates and commonly used for single electron t
 ransistor [4\,5]. Here\, we have synthesized a novel rigid molecular wire\
 , named carbon-bridged oligo(phenylenevinylene)s (COPVn)\, which has flat 
 and rigid -conjugated structure and were demonstrated high electron tra
 nsfer (ET) rate [6\,7]. HS-COPV2-SH and HS-COPV6-SH wires with different l
 ength are chosen and introduced into electroless Au plated nanogap electro
 des studied by low-temperature probe and onto metal surface measured by UH
 V-STM. We have established the fabrication process of stable nanogap elect
 rodes by combining top-down process of electron-beam lithography and botto
 m-up process of electroless-Au plating (ELGP)\, in which the gap separatio
 n can be controlled at nearly 3.0 nm in this experiments with the yield of
  90% due to a self-terminating mechanism of ELGP [8-10]. These ELGP nanoga
 p electrodes are stable up to 170 C annealing\, and are useful for the 
 platform of nanogap devices such as single-electron transistors with ideal
  Coulomb diamonds and availability of logic operations [11-13]. The target
  molecular wires were introduced between Au electrodes and measured by low
 -temperature probe system. The temperature of the system is 9 K and pressu
 re is controlled near 10-5 Pa. The projects concerning UHV-STM measurement
  were conducted by UNISOKU in Tokyo Tech and OMICRON in RIKEN\, separately
 . We introduced HS-COPV2-SH molecular wires and C8S mix SAM onto Au(111) s
 urface\, and scanned the surface in 3.010-8 Pa condition with temperatu
 re of nearly 70 K. In order to obtain higher resolution images and scannin
 g tunneling luminescence spectra\, the HS-COPV6-SH molecular wires were ch
 osen and introduced onto Ag(111) surface\, and were measured in 3.010-9
  Pa with temperature of nearly 4.7 K.\nFor HS-COPV6-SH molecular wires\, w
 e have observed Coulomb blockade and resonant tunneling phenomena both in 
 nanogap electrodes and STM system. Single electron tunneling and coherent 
 resonant tunneling through molecular orbitals are expected. The similar re
 sults can be also found in HS-COPV2-SH molecular wires. Furthermore\, we f
 ound current abrupt change in COPV2 nanogap device\, whose reason remains 
 unexplored.\nThis work was carried out in collaboration with Mr. K. Hashim
 oto\, Mr. M. Koshimura\, Mr. K. Kimura\, Mr. Y. Ito\, and Dr. N. Umezawa\,
  Dr. H. Imada\, Dr. H. Walen. This study was partially supported by MEXT E
 lements Strategy Initiative to Form Core Research Center from the Ministry
  of Education\, Culture\, Sports\, Science\, and Technology\, Japan\; the 
 Collaborative Research Project of Laboratory for Materials and Structures\
 , Tokyo Institute of technology\; the Collaborative Research Project of th
 e Institute of Chemical Research\, Kyoto University (Grant 2016-74)\; the 
 BK Plus program\, Basic Science Research program (NRF-2014R1A6A1030419).\n
   \nReferences\n[1]	Nature Nanotech. 4\, 551-556 (2009)\n[2]	Nature Nanote
 ch. 3\, 569-574 (2008)\n[3]	Nature Nanotech. 1\, 173-181 (2006)\n[4]	Natur
 e 417\, 722-725 (2002)\n[5]	Nature 407\, 57-60 (2000)\n[6]	J. Am. Chem. So
 c. 134\, 19254-19259 (2012)\n[7]	Nature Chem. 6\, 899-905 (2014)\n[8]	Appl
 . Phys. Lett. 91\, 203107(3) (2007)\n[9]	Nanoscale 4\, 7161-7167 (2012)\n[
 10]	RSC Advances 5\, 22160-22167 (2015)\n[11]	ACS Nano 6 2798-2803 (2012)\
 n[12]	Jpn. J. Appl. Phys. 49 090206(3) (2010)\n[13]	Nanoscale 8 4720-4726 
 (2016)\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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