Technological progress in high-density data storage largely relies on the miniaturization of memory devices. To this end, atomically thin materials that set the physical limit for a minimal device-feature size could allow for further memory downscaling. Now, contrary to the commonly accepted belief that non-volatile switching cannot occur in monolayer sheets, R. Ge et al. show single-layer memory devices in a typical vertical metal−insulator−metal (MIM) configuration.
The researchers tested four different monolayer transitional metal dichalcogenides (TMDs) in a crossbar MIM device referred to as an atomristor. The atomic memristor exhibits non-volatile resistance switching that requires no electroforming step, has an on/off ratio above 104 and occurs at programming voltages below 1 V. The highly crystalline TMD monolayers form sharp interfaces and clean tunnel barriers with the Au contacts resulting in a significantly reduced leakage current. The experimental results confirm retention of non-volatile states for up to one week and high mechanical cycling endurance in the best-performing MoS2 atomic switch. Unlike the previous demonstration of a lateral atomic MoS2 device, the vertical atomristor is better fit for real applications owning to its smaller footprint and low energy consumption.