Resistive Switching in ZnO Nanorods/Graphene Oxide Hybrid Multilayer Structures

Multilayer structures of graphene oxide-zinc oxide nanorods (GO-ZnONRs) hybrids are successfully grown for use as an active material in resistive switching random access memory (RRAM) devices. A considerable reduction in the OFF current is achieved through a layer-by-layer growth of GO-ZnONR multilayers up to three repeating layers as the active material. The scanning electron microscope images and X-ray diffraction patterns of the hybrid multilayer structures reveal that vertically oriented ZnONRs are sandwiched between GO sheets. A Raman analysis shows that the G peak position in GO redshifts, due to the COZn bonding at interfaces of the hybrid multilayer structures. X-ray photoelectron spectroscopy analysis of the hybrid multilayer structures also confirms the growth of GO on ZnONRs and secondary ZnONRs on GO, through a COZn bonding. This study realizes the growth of vertically oriented secondary and tertiary ZnONRs on GO, accompanying a tuning of photoluminescent emission wavelength. This hybrid multilayer structure-based resistive memory device exhibits a stable resistive switching behavior with an ON–OFF ratio up to 3.3 × 105, which is higher by three orders of magnitude than the ON–OFF ratio of a single-layer ZnONRs based device.