Near-Infrared Artificial Optical Synapse Based on the P(VDF-TrFE)-Coated InAs Nanowire Field-Effect Transistor.

Area of Science:

• Materials Science
• Neuroscience
• Electrical Engineering

Background:

• Optical synapses are crucial for optical neuromorphic computing, with applications in AI and visual perception.
• Infrared (IR) optical synapses are underdeveloped, despite the potential of materials like Indium Arsenide (InAs) nanowires (NWs) for IR detection due to their narrow bandgap and high surface-to-volume ratio.

Purpose of the Study:

• To demonstrate the first near-infrared (NIR) optical synapse.
• To investigate the synaptic behaviors of a poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))-coated InAs nanowire field-effect transistor (FET) under NIR illumination.
• To elucidate the working mechanism behind the observed optical synaptic functions.

Main Methods:

• Fabrication of a P(VDF-TrFE)-coated InAs NW FET.
• Characterization of the device's photoresponse under 750 nm laser illumination.
• Evaluation of optical synaptic behaviors, including excitatory postsynaptic current (EPSC) and plasticity (paired-pulse facilitation (PPF), short-term plasticity (STP) to long-term plasticity (LTP) transformation) in response to NIR light pulses.

Main Results:

• The P(VDF-TrFE)-coated InAs NW FET achieved a high responsivity of 839.3 A/W at 750 nm.
• The device demonstrated key optical synaptic functions, mimicking biological synapses.
• The ferroelectric polarization effect in the P(VDF-TrFE) layer was identified as the mechanism governing photogenerated carrier trapping and de-trapping.

Conclusions:

• The P(VDF-TrFE)-coated InAs NW FET successfully functions as a NIR optical synapse.
• The ferroelectric P(VDF-TrFE) layer plays a critical role in enabling synaptic plasticity.
• This work offers significant advancements for developing artificial neural networks and visual perception systems.