A Reliable High-Performance Floating-Gate Transistor Based on ZrS2 Native Oxidation for Optoelectronic Synergistic Artificial Synapses

Abstract

Floating-gate transistors (FGTs), considered the most promising structure among three-terminal van der Waals (vdW) synaptic transistors, possess superiorities in improved data retention, excellent endurance properties, and multibit storage capacity, thereby overcoming the von Neumann bottleneck in conventional computing architectures. However, the dielectric layer in FGT devices typically depends on atomic layer deposition or mechanically transferred insulators, posing several challenges in terms of device compatibility, manufacturing complexity, and performance degradation. Therefore, it is crucial to discover dielectrics compatible with two-dimensional (2D) materials for further simplifying FGT structures and achieving optimal performance. Here, we present a controllable and reliable oxidation process to convert the 2D semiconductor ZrS₂ into its native oxide ZrO_x and combine ZrO_x/ZrS₂ with the MoS₂ channel to form MoS₂/ZrO_x/ZrS₂ FGT, which exhibits a high on/off ratio of 10⁷, a wide memory window of 101 V, a long retention time of 10³ s, a large storage capacity of 7 bits, an excellent PPF index of 269.4%, and low power consumption of 5 pJ. Under photoelectric stimulation, the device stimulates various biological synapse behaviors, including associative memory function and retina-like adaptation. In particular, the device achieves information storage and erasure under solely optical stimulation, exhibiting high consistency with synaptic weight modulation in optogenetics and outstanding optoelectronic storage performance. These results suggest that our work provides a novel and effective approach for simplifying FGT structures and enhancing their performance, holding significant potential for application in next-generation multifunctional memory devices and systems.

Keywords: 2D materials; artificial synapse; floating gate transistors; native oxidation; optoelectronic synergy.