Epitaxial growth of full-vdW α-In2Se3/MoS2 heterostructures for all-in-one sensing and memory-computing artificial visual system

Van der Waals (vdW) ferroelectric-semiconductor heterojunction provides reconfigurable band alignment based on optical/electrical-assisted polarization switching, which shows great potential to construct artificial visual neural systems. However, the mechanical exfoliation fabrication scheme for proof-of-concept demonstrations and fundamental studies is cumbersome and not scalable for practical application. Here, we present a synthetic strategy for the large-scale and high crystallinity growth of planar/vertical α-In2Se3/MoS2 heterojunctions by dynamically tuning the growth temperature. Furthermore, based on the α-In2Se3/MoS2 heterostructures, photo-synapse devices are designed and fabricated to simulate visual neural systems functions, including multistate storage, optical logic operation, potentiation and depression, paired-pulse facilitation (PPF), short-term memory (STM), long-term memory (LTM), and Learning-Forgetting-Relearning. By coupling the spatiotemporally relevant optical and electric information, the device can mimic the superior biological visual system's light adaptation and Pavlovian conditioning. This work provides a strategy for dynamically tuning the orientation of ferroelectric-semiconductor heterojunction stacks and will give impetus to applying all-in-one sensing and memory-computing artificial vision systems.