Effects of single-pulse Al2O3 insertion in TiO2 oxide memristors by low temperature ALD

Al2O3/TiO2 multilayer structures were fabricated by atomic layer deposition (ALD) to examine the effect of Al2O3 on the resistive switching behavior of TiO2 thin films. The doping process via ALD consisted in the fabrication of a multilayer structure, in which Al2O3 single layers were periodically inserted into TiO2 films during ALD. The presence of Al atoms induced localized structural and chemical variations that allowed tuning the electrical response of TiO2 devices. Multilayer and doped samples were deposited at low temperature (100 degrees C), using TiCl4 and TMA as metal precursor and H2O as oxidation source. The memristive behavior of Pt/TiOx:AlOy/Pt symmetric devices was tested in voltage sweep mode, showing a bipolar switching with stable high and low resistance states. The variation of doping concentration of Al2O3 in the TiO2 film obtained by ALD allowed to tune switching voltages, resistance values and R-OFF/R-ON ratio. The fine control of these variables adds a degree of freedom in the control of MIM memristors, exploiting the combination of different binary oxides and producing devices with highly defined and tunable electrical properties.