A. M. Ionov

Resistive switching effect in thin-film heterojunctions based on electron-doped Nd2 − xCexCuO4 − y superconductor

Thin-film heterojunctions Nd2 − xCexCuO4 − y/Ag were obtained. The bipolar effect of resistive switching in these heterostructures was detected and investigated. X-ray diffraction data indicate the presence of a second phase in thin films; along with the basic phase Nd2 − xCexCuO4 − y, it affects the behavior of the interface of investigated heterojunctions and leads to an alteration of the type of conductivity. The threshold frequency of alternating voltage at which the resistive switching effect is observed in heterojunctions was detected.

Diffusion of silver in TiSe2 single crystals

Diffusion of deposited silver through the surface of TiSe2 single crystals has been investigated. It is found that diffusion occurs only near lattice defects. The X-ray photoelectron spectra of TiSe2 single crystals with in situ deposited silver have been studied. It is found that, upon annealing in the spectrometer chamber, silver does not form chemical bonds with the host lattice.

Resistive switching in mesoscopic heterostructures based on Nd 2– x Ce x CuO 4– y epitaxial films

Reversible and stable bistable resistive switching were observed in planar-type junctions Nd2–xCexCuO4–y/Nd2–xCexO1.75/Ag. It was shown that current transport in such junctions has a diode character with Schottky-like barriers in highly doped semiconductors. It was revealed that the key factor for switching is the presence of the second phase Nd2–xCexO1.75, deficient in oxygen, epitaxially germinated at the Nd2–xCexCuO4–y surface.

Resistive switchings and diode properties of heterostructures based on epitaxial superconducting Nd2–xCexCuO4–y films

Reversible and reliable bistable resistive switchings are observed in planar-type Nd2–xCexCuO4–y/Nd2–xCexO1.75/Ag junctions based on the Nd2–xCexCuO4–y superconducting films. Investigation of electronic structure of surface of the Nd0.5Ce0.5O1.75/Nd2–xCexCuO4–y via high-resolution X-ray photoelectron spectroscopy and atomic force microscopy (AFM) show that the key factor for the switchings is the presence of an oxygen-deficient Nd2-xCexO1.75 phase, epitaxially intergrown on surfaces of Nd2–xCexCuO4–y.

Si(hhm) surfaces: Templates for developing nanostructures

The fabrication of ordered low-dimensional structures on clean and metal-atom-decorated stepped Si(557) and Si(556) surfaces is discussed. The formation conditions and atomic structure of regular step systems on clean Si(557) 7 × 7 and Si(556) 7 × 7 surfaces are studied. The atomic structure of stepped Si(hhm), Ag/Si(557), and Gd/Si(557) surfaces is studied using high-resolution scanning tunneling microscopy and low-energy electron diffraction. The possibility of fabricating 1D and 2D structures of gadolinium and silver atoms on the Si(557) surface is demonstrated.

Resistive switching and diode properties of mesoscopic niobium oxide-based structures

The bipolar effects of resistive switching (BRS) in mesoscopic heterostrucures based on amorphous and crystalline niobium oxide films are considered. The BRS effect is more pronounced in the structures based on multiphase nanocrystalline niobium oxide films. It is shown that the threshold frequency for observing the BRS effect is of the order of 104 Hz. Switching is controlled via oxygen electrodiffusion to vacancies as the doping level of the contact area and the resistive properties of the heterocontact change.