Yutaka Majima

In this review, we describe recent progress made in the study of nanoparticles characterized by scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). Basic principles of STM measurements and single-electron tunneling phenomena through a single NP are summarized. We highlight the results of electrical and photonic properties on NPs studied by STM and STS. Because nanoparticles are single-digit nanometre in diameter, a single-electron transport on individual nanoparticles

The new displacement current measuring system used for detecting the dynamic behavior of monolayers at the air-water interface is described. It basically consists of a film balance, a light source and a pair of electrodes connected to each other through a sensitive ammeter. Here, one electrode is suspended in air and the other electrode is placed in the water. Using the system, displacement current generated from a single monolayer by either the application of surface pressures or the photoirrad

Robust nanogap electrodes for nanodevices with a separation of 3.0 ± 1.7 nm were simultaneously mass-produced at a yield of 90% by a combination of electron beam lithography (EBL) and electroless gold plating (EGP). Nanogap electrodes demonstrated their robustness as they maintained their structure unchanged up to temperatures of 170 °C, during the isotropic oxygen plasma ashing removal of the amorphous carbon overlayer resulting from scanning electron microscopy observations, therefore maintain

Tribenzosubporphyrins are boron(III)-chelated triangular bowl-shaped ring-contracted porphyrins that possess a 14π-aromatic circuit. Their flat molecular shapes and discrete molecular orbital diagrams make them ideal for observation by scanning tunneling microscopy (STM). Expanding their applications toward single molecule-based devices requires a fundamental knowledge of single molecular conductance between tribenzosubporphines and the STM metal tip. We utilized a tungsten (W) STM tip to invest

Molecular ruler electroless plated (MoREP) nanogap electrodes: gap separation can be controlled between 2.5 and 3.3 nm by surfactant C_nTAB.

Dynamic behavior of fatty acid monolayers at the air-water interface was investigated using a current-measuring technique, where a current-area ( I - A ) isotherms was monitored together with a surface pressure-area (π- A ) isotherm during the compression of a monolayer at the air-water interface. In liquid phase, current I decreased at a constant rate with compression, due to a change in the vertical component of the dipole moment of fatty acid molecules. At the liquid-solid phase transition, a

Robust Pt-based nanogap electrodes with a 10 nm scale ultrafine linewidth were fabricated on SiO2/Si substrates by electron-beam lithography. The structures of the fabricated electrodes remained unchanged up to temperatures of 773 K. The robust thermal stability of the fabricated electrodes in comparison with that of Au-based nanogap electrodes was discussed based on Rayleigh instability. A chemically assembled single-electron transistor was prepared by chemisorbing a 6 nm sized Au nanoparticle

Organic molecular wires that operate stably at ambient temperatures are a necessary first step toward practical and useful molecular-scale electronic devices, which have thus far been hampered by many factors, including the structural and electron configurational instability of organic molecules. We report here that a single disulfanyl carbon-bridged oligo(phenylenevinylene) (COPV6) molecule embedded between thermally stable electroless Au-plated electrodes of a 4 nm nanogap undergoes coherent r

We show the control of a charging energy in chemically assembled nanoparticle single-electron transistors (SETs) by altering the core diameter of Au nanoparticles. The charging energy is a fundamental parameter that decides the operating temperature of SETs. Practical application of SETs requires us to regulate the value of the charging energy by tuning the diameter of quantum dots. In this study, we used 3.0, 5.0 and 6.2 nm diameter synthesized Au nanoparticles as a quantum dot in the SETs. The

Abstract Hydrogen (H 2 ) is increasingly employed in industrial applications, such as developing hydrogen fuel cells for vehicles and power plants. However, H 2 explodes at a concentration limit of 4%, necessitating the development of ultrasensitive hydrogen sensors capable of early‐stage detection of hydrogen leaks. In this study, nano‐patterned polycrystalline cupric oxide (CuO) nanowire array nanogap gas sensors with voids are fabricated using electron‐beam lithography and ex situ oxidization

Rhombic Coulomb diamonds are clearly observed in a chemically anchored Au nanoparticle single-electron transistor. The stability diagrams show stable Coulomb blockade phenomena and agree with the theoretical curve calculated using the orthodox model. The resistances and capacitances of the double-barrier tunneling junctions between the source electrode and the Au core (R1 and C1, respectively), and those between the Au core and the drain electrode (R2 and C2, respectively), are evaluated as 4.5

A new simultaneous measuring system for tunneling current and surface potential has been developed. The distance ( d ) between a sample and an electrochemically etched tungsten tip is changed sinusoidally with high precision. The tunneling current flows periodically in accordance with the vibration of the tip when d becomes as small as a few nm. The surface potential is measured using the principle of the Kelvin method in which the displacement current due to the presence of surface potential an

A single-molecule single-electron transistor (SM-SET) consisting of a π-conjugated quinoidal-fused oligosilole derivative, Si-2, of radius 0.75 nm and heteroepitaxial spherical (HS) Au/Pt nanogap electrodes is demonstrated. Si-2 with two inner silicon atoms and two ethylenethiol groups at both ends is chemisorbed by an S–Au bond between HS-Au/Pt nanogap electrodes fabricated by combining electron-beam lithography and electroless Au plating. An ideal Coulomb staircase, Coulomb oscillation, and Co