Large conductance switching nonvolatile memories based on p-ZnS nanoribbon/n-Si heterojunction

Abstract

A new structure nonvolatile memory, with large conductance switching (on/off ratio > 10⁶), has been constructed from a p-ZnS nanoribbon (NR)/n-Si heterojunction. The p-type ZnS NRs were obtained using cuprous sulfide (Cu₂S) as the Cu dopant. Excellent Ohmic contact to p-type ZnS NRs was achieved by using a Cu/Au bilayer electrode, which contributed to the formation of the thin Cu₂S interfacial layer between the electrode and the NR, as confirmed from the combined X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) analysis. These devices exhibit a stable and reproducible hysteresis and excellent memory characteristics with a long retention time of 1 × 10⁵ s and good endurance >6 months at room temperature. The electrical switching behavior could be attributed to the charge trapping and detrapping in interface states at the junction. The approach could potentially provide a viable way to create new advanced nonvolatile memory devices with simple structure and to fabricate large conductance switching and large-capacity data storage.