Crossbar arrays (CBAs) with resistive random access memory (ReRAM) constitute an established architecture for high-density memory. However, sneak paths via unselected cells increase the total power consumption of these devices and limit the array size. To eliminate such sneak-path problems, we propose a Ti/GaOx/NbOx/Pt structure with a self-rectifying resistive-switching (RS) behavior. In this structure, to reduce the operating voltage, we used a Ti/GaOx stack to increase the number of trap sites in the RS GaOx layer through interfacial reactions between the Ti and GaOx layers. This increase enables easier carrier transport with reduced electric fields. We then adopted a NbOx/Pt stack to add rectifying behavior to the RS GaOx layer. This behavior is a result of the large Schottky barrier height between the NbOx and Pt layers. Finally, both the Ti/GaOx and NbOx/Pt stacks were combined to realize a self-rectifying ReRAM device, which exhibited excellent performance. Characteristics of the device include a low operating voltage range (-2.8 to 2.5 V), high on/off ratios (∼20), high selectivity (∼104), high operating speeds (200-500 ns), a very low forming voltage (∼3 V), stable operation, and excellent uniformity for high-density CBA-based ReRAM applications.
Keywords: Schottky emission; crossbar array; resistive switching; selectivity; self-rectifying.