Artificial Synapses Based on WSe Homojunction via Vacancy Migration.

Artificial synapses based on two-dimensional (2D) transition metal dichalcogenides (TMDs) materials have attracted wide attention to boost the development of neuromorphic computing in recent years. Various structures have been adopted to build 2D-material-based artificial synapses. In lateral- and vertical-structures, the realization of synaptic function mainly results from the migration of the defects and vacancies, which requires the strong ion diffusion ability. Here, we successfully demonstrate an artificial synapse based on lateral WSe homojunction. The migration of Se vacancies from the thin region to the thick region has been promoted by applying negative gate voltage, resulting in n-type doping in the thick region due to the accumulation of Se vacancies, which would diminish the barrier width of the metal-semiconductor junctions in the thick region. Consequently, the transformation from a high-resistance state (HRS) to a low-resistance state (LRS) is achieved. Significantly, our device can efficiently emulate the biological synaptic functions with a large synaptic weight change. Additionally, the transition from short-term memory (STM) to long-term memory (LTM) can be accomplished with a simpler structure, which would be beneficial to realizing the large-scale integration of transistor-based artificial synapses.