Nanoscale insights on phase transition dynamics of doped VO2 for memristor devices

Abstract

This study utilized co-sputtering to fabricate Mo-doped VO2 films and identified an optimal concentration exhibiting a lower phase transition temperature (Th = 55.8 °C) and a broader hysteresis window (Δ T = 13.6 °C). At the atomistic scale, it is demonstrated that Mo dopant-induced localized strain accelerates the phase transition, which leads to the relaxation of the tetragonal structure. Furthermore, the effects of Mo doping on the phase transition process and electrical properties are characterized at the nanoscale using conductive atomic force microscopy and Kelvin probe force microscopy, and the potential application in selectors can be evaluated. The results indicated that Mo doping destabilizes the M1 phase by introducing a high density of electrons, thereby significantly reducing the electron–electron interactions as per the Mott model. Moreover, the device exhibited stable threshold and memristive properties at room temperature, quickly switching from high to low-resistance states at a threshold voltage of 2.37 V and maintaining stability over more than 1000 cycles with a selectivity >102. The present work not only highlights the role of Mo doping in enhancing the functional properties of VO2 but also demonstrates its feasibility in high-performance selectors devices.