Engineering of atomic layer deposition process for titanium-aluminum-oxide based resistively switching medium

Resistive-switching Al2O3-doped TiO2 thin films with thicknesses of around 10 nm were grown by atomic layer deposition, using TiCl4 and Al(CH3)3 as the metal precursors and H2O as the oxygen source at 350 °C. A novel approach, based on the sequential pulsing of titanium and aluminum precursors, followed by a H2O pulse supplied only after the aluminum precursor pulse, was exploited to create diffuse TixAl1–xOy layers in the TiO2 host media, in order to tune the electrical properties. The films were deposited on substrates coated with conductive RuO2 to promote the epitaxial growth of rutile-phase dielectric on the RuO2 bottom electrode. Examination of the switching behavior confirmed the possibility to reduce the currents in the high resistance state, increase the difference between the high and low resistance states, and obtain multilevel resistive switching by adjusting the aluminum content and distribution in the films.