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

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 (approximate to 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.