An optically controlled synaptic device based on a PdSe₂/α-In₂Se₃ vdW heterostructure FET

Area of Science:

• Materials Science
• Nanotechnology
• Neuroscience

Background:

• Neuromorphic hardware aims to overcome the von Neumann bottleneck using synaptic devices.
• Achieving bidirectional optical control in these devices is a significant technical hurdle.
• 2D materials offer unique properties for advanced electronic and optoelectronic applications.

Purpose of the Study:

• To develop an optically controlled synaptic device with ferroelectric-assisted tunability.
• To emulate spike-dependent plasticity and achieve bidirectional optical control.
• To demonstrate the device's potential in logic operations and artificial neural networks.

Main Methods:

• Fabrication of an all 2D heterostructure field-effect transistor (FET) using few-layer PdSe2 and α-In2Se3.
• Characterization of excitatory and inhibitory synaptic responses under different wavelengths (406-520 nm and 642-980 nm).
• Demonstration of logic gate operations and training of a three-layer artificial neural network (ANN) on the MNIST dataset.

Main Results:

• The device exhibited tunable excitatory and inhibitory synaptic responses controlled by optical and electrical signals.
• Enhanced retention time of post-synaptic current (PSC), responsivity (R), and detectivity (D) were observed due to the ferroelectric properties of α-In2Se3.
• High recognition accuracy (96-97%) was achieved in an ANN for handwritten digit recognition using optical inputs.

Conclusions:

• The developed 2D heterostructure FET is a promising candidate for versatile optically controlled neuromorphic devices.
• Ferroelectric properties of α-In2Se3 significantly enhance device performance and synaptic plasticity.
• This work provides a foundation for on-chip optical communication, optoelectronic logic, and Internet of Things (IoT) applications.