Mimicking synaptic functionality with an InAs nanowire phototransistor.

Area of Science:

• Materials Science
• Neuroscience
• Electrical Engineering

Background:

• Neuromorphic computing aims to replicate brain functions for efficient information processing.
• Developing artificial synaptic devices is crucial for advancing neuromorphic systems.
• Persistent photoconductivity in semiconductor nanowires offers potential for novel device functionalities.

Purpose of the Study:

• To demonstrate a nanowire phototransistor exhibiting synaptic behavior.
• To investigate the role of persistent photoconductivity in achieving synaptic functions.
• To explore the potential of this device for neuromorphic applications.

Main Methods:

• Fabrication of a single crystalline indium arsenide (InAs) nanowire phototransistor.
• Utilizing a native indium oxide layer as a photogating layer (PGL).
• Characterization of the device's photoresponse and synaptic behaviors, including short-term plasticity, long-term plasticity (LTP), and paired-pulse facilitation.

Main Results:

• The nanowire phototransistor demonstrated inherent persistent photoconductivity.
• The device successfully mimicked synaptic neuromorphic behaviors in the negative photoresponse range.
• A transition from short-term to long-term plasticity was observed with increasing stimulus intensity, showing cooperativity.
• Synaptic behaviors were attributed to the trapping and detrapping of photo-generated electrons in the PGL.

Conclusions:

• The indium arsenide nanowire phototransistor effectively emulates synaptic functions.
• The device's behavior is governed by persistent photoconductivity and electron dynamics in the photogating layer.
• This nanowire-based photonic synaptic device holds significant promise for future neuromorphic systems and networks.