Evolution of Resistive Switching Characteristics in WO3-x-based MIM Devices by Tailoring Oxygen Deficiency

Abstract: We report on resistive switching (RS) characteristics of W/WO3-x/Pt-based thin film memristors modulated by precisely controlled oxygen non-stoichiometry. RS properties of the devices with varied oxygen vacancy (VO) concentration have been studied by measuring their DC current voltage properties. Switchability of the resistance states in the memristors have been found to depend strongly on the VOs concentration in the WO3-x layer. Depending on x, the memristors exhibited forming-free bipolar, forming-required bipolar and non-formable characteristics. Devices with high VOs concentration (~1*1021 cm-3) exhibited lower initial resistance and memory window of only 15, which has been increased to ~6500 with reducing VOs concentration to ~5.8*1020 cm-3. Forming-free, stable RS with memory window of ~2000 have been realized for a memristor possessing VOs concentration of ~6.2*1020 cm-3. Investigation of the conduction mechanism suggests that tailoring VOs concentration modifies the formation and dimension of the conducting filaments as well as the Schottky barrier height at WO3-x/Pt interface which deterministically modulates RS characteristics of the WO3-x based memristors.