High-performance, multifunctional devices based on asymmetric van der Waals heterostructures

Two-dimensional materials are of interest for the development of electronic devices due to their useful properties and compatibility with silicon-based technology. Van der Waals heterostructures, in which two-dimensional materials are stacked on top of each other, allow different materials and properties to be combined and for multifunctional devices to be created. Here we show that an asymmetric van der Waals heterostructure device, which is composed of graphene, hexagonal boron nitride, molybdenum disulfide and molybdenum ditelluride, can function as a high-performance diode, transistor, photodetector and programmable rectifier. Due to the asymmetric structure of the device, charge-carrier injection can be switched between tunnelling and thermal activation under negative and positive bias conditions, respectively. As a result, the device exhibits a high current on/off ratio of 6 x 10(8) and a rectifying ratio of similar to 10(8). The device can also function as a programmable rectifier with stable retention and continuously tunable memory states, as well as a high program/ erase current ratio of similar to 10(9) and a rectification ratio of similar to 10(7).