The improvement of stable resistive switching in Al/ZnO/Al heterostructures by integration of amorphous carbon layers (Phys. Status Solidi A 3∕2017)

Abstract

Resistive-switching (RS) random access memory (RRAM) has been attracting increased attention as the next-generation nonvolatile memory. To make its reduction reversible in metal-oxide based RRAM, some of studies use noble metal electrodes with a much higher electron affinity for the stable RS. On the other hand, amorphous carbon (a-C), which is a tunable material with a mixture of sp2 and sp3 C, has also been considered as a nonvolatile memory candidate material. It has been demonstrated that the RS mechanism is mostly due to clustering of the existing sp2 sites within the sp3 matrix after applied electric field. Hence, a deliberately designed ZnO/a-C hybrid structure can be utilized to stabilize RS in RRAM performance using Al electrodes as shown by Hua Shu Hsu et al. (article No. 1600739). Devices with a-C inserted layers show better RS properties than those without because the suitable a-C/ZnO interface may act as an oxygen reservoir, providing sufficient oxygen ions for RS effect during the reset process. The results provided a new opportunity to integrate C materials into RRAM devices.