New Mechanism in Ohmic VCM Devices - Prospective and Challenges

Functionalities, propertis and stability of memristors are determined by three main factors – physico-chemical processes materials and operation scheme, where the first two factors are inherently related. It is a of highest priority of the ongoing research to improve memristors in several important aspects including multi-functional use, variability, state stability and degenerative processes. A way to progress in fundamental aspect understandings and applicatoins is to achieve understanding and control over the physical processes involved in the formation of different resistive states and based on this knowledge to design reliable materials system being with predictable and adjustable properties. Several important aspects of the operation principles have been relieved, such as effects of protons and ambient moisture, interface interactions, migration of cations believed to be immobile, nanobattery effect, influence of the capping layers and film thicknesses etc.<br/>In this work, we present a new mechanism observed in ohmic oxide memristors that allows for significant improvement of the device characteristics and stability. The switching performance depends on materials used for electrodes, their electrochemical activity and redox potential. We found that not Schottky barrier is necessary to swithc the devices and reach relibale operation. TI<i>n situ</i> TEM analysis have shown that contribution of different ionic species is responsible for two distinctive switching mechanisms that in turn determine the performance. Based on this knowledge we were able to design devices showing multiple functionalities and with significantly improved characteristics.