Electrically erasable writing properties of ZnS films by conductive atomic force microscopy

Resistive switching cycles were realized in Au/ZnS/substrate (indium-tin oxide (ITO), Cu, Si) structures, and electrically erasable writing operations were achieved in the Au/ZnS/Si structure using conductive atomic force microcopy. High-resolution transmission electron microscopy revealed that high resistance state was a mixture of amorphous and nanocrystalline state, while the frequency response of alternating current conductivity indicated that the low resistance state (LRS) was only nanocrystalline. Electric field and thermal effects contributed to the distribution of conductive defects in the ZnS film, and nearest-neighbor hopping conduction controlled the electrical resistance of the Au/ZnS/ITO structure. X-ray photoemission spectroscopy analysis of conductive defects of ZnS films in the LRS revealed that they were zinc-rich or sulfur-poor. This study confirms the intrinsic resistive switching characteristic of ZnS films, which can serve as nonoxide materials for nonvolatile memory application.