Design and Characterization of Semi-Floating-Gate Synaptic Transistor

Area of Science:

• Materials Science
• Electrical Engineering
• Neuroscience

Background:

• Neuromorphic computing aims to replicate the brain's efficiency.
• Synaptic transistors are key components for hardware-driven neuromorphic systems.
• Achieving short- and long-term plasticity in transistors is crucial for complex learning.

Purpose of the Study:

• To investigate the feasibility of a semi-floating-gate synaptic transistor (SFGST) for energy-efficient neuromorphic systems.
• To demonstrate the capability of the SFGST to exhibit short- and long-term potentiation (STP/LTP) and spike-timing-dependent plasticity (STDP).

Main Methods:

• Fabrication of a SFGST utilizing a poly-Si semi-floating gate (SFG) and a SiN charge-trap layer.
• Utilizing Fowler-Nordheim tunneling for hole injection into the charge-trap layer.
• Employing an embedded tunneling field-effect transistor and a diode for controlled charging and discharging of the SFG.

Main Results:

• The SFGST successfully demonstrated both STP and LTP behaviors.
• Spike-timing-dependent plasticity (STDP) was achieved through controlled SFG charging/discharging.
• The transistor structure is highly miniaturized, suitable for integration.

Conclusions:

• The SFGST is a viable candidate for energy-efficient hardware-driven neuromorphic systems.
• The demonstrated plasticity mechanisms enable complex learning functionalities.
• The SFGST's characteristics support the development of high-density, low-power neuromorphic chips that mimic brain-like operation.