Ultrasensitive Memristive Synapses Based on Lightly Oxidized Sulfide Films

Area of Science:

• Materials Science
• Neuroscience
• Electrical Engineering

Background:

• Biological synapses require high sensitivity for accurate information transmission.
• Memristive synapses exhibit lower sensitivity than biological ones, needing higher voltages for plasticity.
• Enhancing memristive synaptic device sensitivity is an underexplored area.

Purpose of the Study:

• To develop highly sensitive memristive synaptic devices.
• To emulate synaptic functions using low-amplitude electrical stimuli.
• To address the energy consumption of synaptic devices.

Main Methods:

• Fabrication of electrochemical metallization memory cells using lightly oxidized ZnS films.
• Characterization of memristive switching behavior with ultralow SET voltages.
• Emulation of synaptic plasticity (short-term and long-term potentiation) using millivolt-level stimuli.
• Demonstration of memorizing and forgetting dynamics in a 5x5 memristive synapse array.

Main Results:

• Achieved highly controllable memristive switching with SET voltages in the millivolt range.
• Identified a two-layer ZnS film structure (oxidized/unoxidized) responsible for confined filament dynamics at the interface.
• Demonstrated synaptic functions with sensitivity surpassing biological synapses.
• Successfully mimicked dynamic memory processes in a synapse array.
• Highlighted ultralow operating voltage as a solution for energy consumption.

Conclusions:

• Ultrasensitive memristive synapses were realized using lightly oxidized ZnS films.
• The device's high sensitivity stems from its unique two-layer structure and confined filament dynamics.
• These findings offer a pathway to more efficient and sensitive artificial synaptic devices.