Long-Term Multilevel Memory and Synaptic Function Transistors Using 2D MoSe₂/MoS₂ Heterostack Channel

We demonstrate multilevel long- and short-term memory behavior operating at low voltages, based on van der Waals heterostack n-MoSe₂/n-MoS₂ channel field effect transistors (FETs). Our heterostack memory FET exploited the gate-voltage (V_GS)-induced trapping/detrapping phenomena for Program/Erase functioning, which was maintained for long retention times due to the existence of heterojunction energy barrier between MoS₂and MoSe₂. More interestingly, trapped electron density was incrementally modulated by the magnitude of a pulsed V_GS, enabling the heterostack device to achieve multilevel long-term memory. For a practical demonstration, five different levels of drain current were visualized with modulated light emissions after our memory FET was integrated to an organic light emitting diode pixel circuit. In addition, our device was applied to a synapse-imitating neuromorphic memory in artificial neural network. We regard our unique heterostack channel FET to be a novel and promising electron device undertaking multifunctional operations related to upcoming fourth industrial revolution era.