Complementary Switching in 3D Resistive Memory Array

High-density application of 3D vertical crossbar resistive random access memory (3D-VRRAM) is challenging due to sneak leakage paths, which can be combated by using nonlinear low resistance state or complementary resistive switching (CRS). This work presents high-resolution transmission electron microscopy (HRTEM) observation of nanofilaments during resistive switching (RS) in a TiOx/Al2O3-based bilayer submicrometer 3D-VRRAM hybrid device and the reset-failure-induced transformation from RS to CRS. The complete concept is divided into two parts. The first part is RS, where the devices show reliable switching, stable resistance levels, good retention, and moderately higher nonlinear behavior at the low resistance state. The RS mechanism is confirmed by an HRTEM image of a clear formation of conductive Ti5O9 nanofilament followed by a tunnel gap. The second part presents the realization of CRS operation after the reset failure in common electrodeless TiOx/Al2O3-based 3D-VRRAM hybrid devices. The formation of a series resistor along with the filament is the reason behind the evolution of the CRS mode. Higher nonlinearity is achieved under CRS as compared to RS. Further to this, for broad applications, it is essential to examine similar phenomena in other 3D-VRRAM systems.