Programmable memory characteristics of electrodeposited CuOx-based resistive random access memory (ReRAM) can be significantly improved by adopting a bilayer structure with a built-in current limiter. To control the on-current and enhance the device uniformity, the bilayer structure of Pt/CuOx (switching layer)/CuOx (current limiter)/Pt is proposed. This structure is synthesized by controlling solution pH during electrochemical deposition (ECD). The bilayer structure of Pt/CuOx (synthesized at pH 9)/CuOx (synthesized at pH 11.5)/Pt exhibits reliable and uniform self-compliant resistive switching behavior. The origin of resistive switching is attributed to formation and rupture of conductive filaments in the CuOx (pH 9) layer. However, the CuOx (pH 11.5) layer acts as the resistor without resistive switching to control the overall resistance in ReRAM. Reversible "on" and "off" switching occurs with a switching time of 100 ns. Devices based on the bilayer structure showed long data retention and good endurance. This simple use of ECD to improve the memory characteristics of electrodeposited ReRAM offers the opportunity to realize reliable and self-compliant memory devices with low-cost solution processes.
Keywords: bilayer structures; copper oxide; current limiter; electrochemical deposition; resistive switching; self-compliance.