Laser synthesis of non-volatile memristor structures based on tantalum oxide thin films

The amorphous thin TaOx films (x <= 5) of different thicknesses with different levels of oxygen vacancy content, which are promising for use as an active region of non-volatile memristors, were fabricated by the pulsed laser deposition in a drop-free mode on the c-sapphire substrates. The films were obtained from tantalum metal targets at substrate temperatures of 25 degrees C and 350 degrees C in the oxygen pressure range from 0.5 to 50 mTorr. The relationship between the partial oxygen pressure and the optical, electrical, and chemical properties of the films was studied. It was found that the amorphous TaO x phase, which is a source of defects associated with oxygen deficiency, required for the creation of memristors, appears only at low oxygen pressures in the chamber (similar to 5 x10(-4) Torr), this leads to low values resistivity in the films (similar to 10(-3) Ohm . cm). Memristor structures Ag(Pt)/TaOx/TaOy /Ta/c-Al2O3 (x > y) in cross-bar geometry have been created that do not require electroforming, due to the choice of design and deposition conditions. Memristor using two mechanisms of resistive switching based on oxygen vacancies and silver cations showed very reliable RS performance with memory window performance R-ON/R-OFF similar to 10(3) and RESET operating voltage similar to 1 V. (C) 2020 Elsevier Ltd. All rights reserved.