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X-ray spectroscopy

XAFS- study electronic and structure peculiarities of high-k dielectric non-stoichiometric sub-oxides for memristors


  • Dr. Svetlana TRUBINA

Primary authors


  • Dr. Vladimir GRITSENKO (Institute of Semiconductors Physics SB RAS, Novosibirsk State University, Novosibirsk, RussiaNovosibirsk, Russia;)
  • Dr. Kristina KVASHNINA (ESRF, 38043 Grenoble, France; HZDR, Institute of Resource Ecology, 01314, Dresden, Germany)
  • Dr. Vladimir ALIEV (Institute of Semiconductors Physics SB RAS, Novosibirsk, Russia)
  • Dr. Simon ERENBURG (Nikolaev Institute of Inorganic Chemistry SB RAS, Budker Institute of Nuclear Physics SB RAS)
  • Dr. Damir ISLAMOV (Institute of Semiconductors Physics SB RAS, Novosibirsk, Russia; Novosibirsk State University, Novosibirsk, Russia)


Neural and neuromorphic networks that mimic brain functions are used in various fields of science and technology. To create more efficient neural networks, it is required to expand the element base with new instruments with a memory effect. This is the property of a memristor, a passive device whose resistance can be changed by passing a certain current pulse through it. The memristor is a metal-dielectric-metal structure with a dielectric with a high dielectric constant (high-k dielectric). In this paper, using the XAFS spectroscopy methods, the microstructural properties of a number of possible high-k dielectric elements for memristor structures have been studied. These are oxides HfOx, ZrOx, TaOx with different values of "x". It has been established that the samples ZrOx and HfOx studied are a mixture of the phases of ZrO2 and HfO2 oxides and metallic zirconium and hafnium, respectively. The microstructural characteristics for the clusters of both phases in the samples are very close to the characteristics of the pure phases. According to the results of our experiments, the observed samples did not show a noticeable decrease in the coordination numbers for zirconium and hafnium atoms in comparison with the coordination numbers of the massive phases, which allows us to state that the dimensions of single-phase clusters exceed the size of ~ 10 nm. In the XANES spectra for samples of non-stoichiometric TaOx oxides, a long-wavelength shift of the absorption edge relative to the reference oxide is observed, i.e. a decrease in the positive charge on Ta atoms. According to the data of EXAFS, a noticeable increase in the disorder of the structure is observed for the TaOx samples under study as compared to the reference TaO2 oxide. The observed changes in the interatomic distances and coordination numbers, as well as an increase in the disorder of amorphous films with a change in the parameter x (its decrease), is apparently due to the presence in the samples of several oxides of different stoichiometry (in the absence of a metallic phase). This results are in accordance with known literature data.

This work was carried out with the financial support of the RSF No 16-19-00002