Memristive Effect in Ta/TaOx/Ta Structures Obtained by Laser Synthesis

Various materials that ensure the creation of volatile and nonvolatile memristor structures are under study in the development of elements of neuromorphic systems. TaOx thin films and memristor structures in the crossbar geometry based on them are synthesized by pulsed laser deposition in the droplet-free mode using mask technologies. TaOx thin films are obtained at different temperatures of the sapphire substrate (25 and 350°C), oxygen pressure in the vacuum chamber (from 0.5 to 80 mTorr), and wavelength of the ablation radiation (248 and 532 nm). High-resolution X-ray diffraction studies of films make it possible to determine the conditions for the preparation of films with the formation of nanocrystallites and the dependence of the size of nanocrystallites on the preparation conditions. The composition of the films and the degree of oxidation of tantalum are determined by X-ray photoelectron spectroscopy. The two-probe method is used to study the current–voltage characteristics (I—V characteristics) of the films at unipolar and bipolar voltage scanning. The nonvolatile memristive effect in Ta/TaOх/Ta/с-Аl2O3 thin-film structures is revealed during measurements of the I—V characteristics in the planar and crossbar geometry.