Synaptic transistor with a reversible and analog conductance modulation using a Pt/HfOx/n-IGZO memcapacitor

Area of Science:

• Materials Science
• Neuroscience
• Electrical Engineering

Background:

• Biological synapses exhibit analog and reversible plasticity, crucial for learning and memory.
• Mimicking synaptic behavior in electronic devices is key for developing neuromorphic computing architectures.
• Memcapacitors offer a promising route to emulate synaptic functions due to their variable capacitance.

Purpose of the Study:

• To demonstrate a synaptic transistor that emulates biological synaptic motion.
• To utilize the memcapacitance characteristics of a Pt/HfOx/n-indium-gallium-zinc-oxide (IGZO) memcapacitor for synaptic emulation.
• To investigate the analog, polarity-dependent, and reversible memcapacitance for synaptic weight modulation.

Main Methods:

• Fabrication of a metal-oxide-semiconductor (MOS) capacitor with a Pt/HfOx/n-IGZO structure.
• Characterization of memcapacitance using capacitance-voltage (C-V), capacitance-time (C-t), and voltage-pulse measurements.
• Integration of the memcapacitor into a synaptic thin-film transistor (TFT) and evaluation of its synaptic motion.

Main Results:

• The Pt/HfOx/n-IGZO memcapacitor exhibited analog, polarity-dependent, and reversible memcapacitance.
• Positive voltage pulses led to gradual capacitance increase (potentiation), while negative pulses restored it (depression).
• The synaptic TFT demonstrated gradual drain current modulation mimicking synaptic weight changes.

Conclusions:

• The developed MOS memcapacitor effectively emulates biological synaptic potentiation and depression.
• The synaptic transistor showcases functional synaptic operations through reversible conductance modulation.
• This work presents a viable approach for creating synaptic transistors using Pt/HfOx/n-IGZO memcapacitors for neuromorphic applications.