[21a-S323-1~11] 9.3 Nanoelectronics

▲ [21a-S323-11] Coulomb Staircase on Rigid Carbon-bridged Oligo(phenylenevinylene) between Electroless Au plated Nanogap Electrodes

〇(D)Chun Ouyang^1,2, Yousoo Kim², Kohei Hashimoto³, Hayato Tsuji³, Eiichi Nakamura³, Yutaka Majima¹ (1.Tokyo Tech., 2.RIKEN, 3.Univ. of Tokyo)

Keywords:Coulomb blockade,nanogap device

We previously disclosed that carbon-bridged oligo(phenylenevinylene)s (COPVn) serve as effective molecular wires as demonstrated by photoinduced electron transfer because of their rigid structures to achieve effective π-conjugation. In this presentation, we report stable Coulomb staircase on double barrier tunneling structures consisting of COPV6 and electroless Au-plated nanogap electrodes. The initial structures of the source, drain, and two side gate electrodes of Ti/Au were fabricated on a SiO₂/Si substrate via electron beam lithography and lift-off processes. Electroless Au-plating was carried out to reduce the electrode gaps to ~3 nm, followed by the introduction of a HS-COPV6-SH molecule between the nanogap electrodes by immersing into a solution of HS-COPV6-SH. The schematic structure of the resulting device . We then evaluated the current-voltage (I-V) characteristics at 9 K using a mechanical He-refrigerator-type prober station. Clear and stable Coulomb staircase with two stairs at the both negative and positive bias regions have been observed. Thus obtained experimental I-V characteristic has been fitted based on orthodox model by using five parameters: resistances (R₁, R₂) and capacitances (C₁, C₂) of both barriers and the fractional electron charge present on the Coulomb island Q₀ were evaluated to be 47.4 GW, 10.5 GW, 0.426 aF, 0.404 aF, and 0.1e (e: unit charge), respectively. The obtained R₁ and R₂ values indicate that the COPV6 molecule was chemically anchored with the Au nanogap electrodes by the thiol groups at the both ends and serves as a Coulomb island by taking an advantage of the rigid molecular structure of COPV6.