Final Report Year
2010
Final Report Abstract
We investigated resistive memory switching in different layered materials: perovskite-related titanates and niobates of the series AnBnO3n+2 and the high-Tc superconductor Bi-2212. Switching was performed by out-of-plane current injection. We showed that the transport in -axis direction takes place by tunneling between the conducting planes. The change of the resistance, stable in time, is explained by a change of the doping level in the conducting layers. We propose a model of the doping, where the high energy electrons occupy empty trap levels in the insulating layers. The trapped charges in the insulators act as a floating gate inducing the change of doping in the conducting layers. High energy electrons are essential for the resistive memory switching. Indeed, we showed that in our layered materials the out-of-plane transport is characterized by a significant contribution of the overheated electrons, whose temperature can substantially exceed the temperature of the lattice. The bistable resistive memory switching of the AnBnO3n+2 series renders these materials promising for applications as resistive memory cells. However, considering the demand of up to 10 7 writing cycles without degradation of the cell parameters, the main obstacle in the use of the titanates and niobates is a slow drift of the resistance levels in successive switchings. We believe that the performance of the devices can be substantially improved by a decrease of the tunnel junction area.
