Conductance measurements of nanoscale regions with in situ transmission electron microscopy

Abstract

Conductance measurements of nanostructures with simultaneous transmission electron microscopy (TEM) were performed on thin insulating SrF 2 films (3 nm thick) and Fe-SrF 2 granular films (10 nm thick) deposited on tip-shaped Au electrodes. By using a movable counter electrode, nanoscale regions were selected for investigation. Systematic measurements taken during the deformation of the SrF 2 film by the counter electrode provided a tunnelling barrier height of about 2.5 eV. The conductance of Fe-SrF 2 in nanoscale (~ 500 nm 2 ) showed the Coulomb-staircase-like characteristics at room temperature. The staircase period approximately corresponded to the value estimated from the geometry observed by TEM.The feasibility of this method is briefly described.

In situ TEM studies of local transport and structure in nanoscale multilayer films

“…Coulombblockade-like behavior was demonstrated, even near room temperature. In a similar study, Arita et al [30] measured the conductance of a thin insulating SrF 2 film deposited on an Ag tip and found the tunneling barrier height to be 2.5 eV. Gel et al [31] used the deflection of two cantilevers to modify the distance between a gold-gold quantum point contact.…”

Tunnel Conductance through One or a Few Fe Particles Embedded in an MgO Matrix

“…[10][11][12][13][14] Although some of these instruments did not have the feedback control, the term STM is used to refer to them in this report. Similar experiments have been carried out on a metal-insulator composite film in which metallic nanoparticles were dispersed in an insulator matrix, 15,16) and a clear Coulomb blockade effect was observed at room temperature (RT) when the contact area is small.…”

“…Further details have been described elsewhere. 15,16) During the observations, the electrodes were exposed to an electron beam that generated a background current of a few nA. Because the net tunnel current was on the order of nA, the instability of the electron beam produced a fatal background noise.…”

Tunnel current measurement of MgO and MgO/Fe/MgO nanoregions during TEM observation

“…The electrodes having sharp apexes were made from Au wires (purity: 99.95%) by an ion sputtering method using diamond or graphite powders as the mask material (the ion-shadow method [12]). Examples are shown in Fig.…”