Hf<sub>0.5</sub>Zr<sub>0.5</sub>O<sub>2</sub>/HfO<sub>2</sub>/Hf<sub>0.5 </sub>Zr<sub>0.5</sub>O<sub>2</sub> laminated thin films and CF<sub>4</sub> plasma passivation for improved memory and synaptic characteristics of ferroelectric field-effect transistors

Abstract

In this study, we demonstrate significant advancements in hafnium oxide-based ferroelectric field-effect transistors (FeFET) by integrating two engineering methods: laminated ferroelectric (FE) thin films and CF4-based plasma treatment. Individually, these techniques exhibit specific trade-offs; however, their combined application effectively mitigates these drawbacks, maximizing their synergistic benefits. Compared to the pristine FeFET, our results demonstrate an improvement in endurance by more than one order of magnitude, while maintaining the same memory window (MW) at 1.2 V, through the application of the proposed engineering. Furthermore, the combined approach significantly enhances the synaptic properties of FeFETs, making them more suitable for analog synapse applications in neuromorphic computing. Specifically, the Gmax/Gmin ratio increased from 4 to 7, the asymmetry value decreased from 4.68 to 3.44, and the number of states rose from 75 to 100. Lastly, through MNIST dataset-based accuracy simulation, the proposed device achieved an inference accuracy of 80%, representing a 10% improvement over the pristine device. These findings suggest that the simultaneous utilization of FE lamination and plasma treatment can be a knob for developing high-performance FeFET-based analog synapses, advancing their potential in memory and neuromorphic computing technologies.