Optically controlled synaptic device based on PdSe2 / α-In2Se3 vdW heterostructure FET

Abstract

Visual synaptic devices hold great promise for advanced neuromorphic hardware, offering a viable solution to the von Neumann bottleneck. Yet, achieving bidirectional optical control remains a considerable challenge. Herein, we demonstrate an all 2D heterostructure FET consisting of few-layer PdSe2 and α-In2Se3 , designed as a fully optical controlled synaptic device. The device emulates multiple forms of spike-dependent plasticity, exhibiting excitatory and inhibitory synaptic responses in 642-980 nm and 406-520 nm spectral range, respectively. By leveraging the coupled ferroelectric and optical properties of In2Se3, the device achieves an extended retention time of post-synaptic current (PSC) and enhanced device performance in terms of responsivity (R) and detectivity (D) over PdSe2 -based counterparts. Moreover, the optically induced excitatory and inhibitory synapse can be modulated by electrical gate pulse, utilizing the spontaneous polarization of α-In2Se3. Logic gate operations (OR and AND) were demonstrated using 642 nm, 785 nm and 406 nm wavelengths as optical inputs. In addition, three-layer artificial neural network (ANN) was trained to recognize 28×28 pixels handwritten MNIST dataset by backpropagation algorithm demonstrating high recognition accuracy of 96% and 97% under 642 nm and 406 nm, respectively. This study provides an effective strategy for the development of versatile optically controlled neuromorphic devices as fundamental building blocks for on-chip optical communication, optoelectronic logic, and Internet of Things (IoT) applications.