Thermally Tunable Analog Memristive Behaviors in Sulfurized In2Se3 Nanoflakes for Bio-Plausible Synaptic Devices

Combining the intrinsic superiorities of two-dimensionalmaterialsand the emerging demand for neuromorphic computing, two-dimensionalmemristors have achieved huge advances in materials exploration andsynaptic functionality emulation. However, their neuromorphic applicationsare still in the early stage since digital memristive behaviors formost of them are inconsistent with gradual biological synaptic plasticity.Here, we developed a simple approach to realize analog and thermaltunable memristive behaviors by introducing sulfur vacancies in CVD-grownIn(2)Se(3) nanoflakes through secondary sulfurizationtreatment. The density functional theory and ab initio molecular dynamicssimulations confirm that sulfurized and defective In2Se3 can remain thermal stability at elevated temperatures upto 550 K. Therefore, we systematically investigated the temperature-dependentanalog and tunable memristive behaviors and realized linear weightupdate with ultrawide dynamic range in sulfurized In2Se3 at high temperatures. The developed memristive device successfullyemulates bio-realistic synaptic functionalities including transformationfrom short- to long-term plasticity, paired-pulse facilitation, posttetanicpotentiation, spike-amplitude-dependent plasticity, spike-rate-dependentplasticity, and spike-time-dependent plasticity effects. It is unveiledthat the formation energy of sulfur vacancy is greatly smaller thanthat of selenium, while their roughly same migration barriers canbe modulated by electric field and temperature. Therefore, we putforward that the applied electric field can mediate vacancy migrationin the sulfurized In2Se3 to gradually regulatethe conductance, thereby realizing the emulation of synaptic plasticity.This work provides a promising approach to designing bio-plausiblememristive devices for robust neuromorphic applications at high temperatures.

Automated summary

Analog and thermal tunable memristive behaviors were achieved in sulfurized In2Se3 nanoflakes, allowing for the emulation of bio-realistic synaptic functionalities. This provides a promising approach for robust neuromorphic applications at high temperatures.