A Dual‐Mode Programing Nonvolatile Floating‐Gate Memory with Convertible Ohmic and Schottky Contacts

Abstract Research on van der Waals heterostructures based on stacked two‐dimensional atomic thickness crystals has received considerable attention because of their unique characters and great potential applications in flexible transparent electronics and optoelectronics. In this study, a nonvolatile memory device with a few‐layer bipolar material WS₂ as channel and charge‐trapping layers is designed with a floating‐gate structure in which charges (electrons and holes) can be stored in the charge‐trapping layer using a dual‐mode processing program by changing the metal–semiconductor contact type. The device exhibits different programming currents during programming, in particular, the device has a low programming current for programming voltages ˂20 V. Moreover, the heterostructure exhibits a remarkable long retention time (≈10,000 s), with no apparent degradation and a strong endurance, retaining its original performance even after 1,000 programming/erasing cycles. This study proposes a novel method for reducing power consumption while programming to facilitate artificial synapse applications.