A multi-timescale synaptic weight based on ferroelectric hafnium zirconium oxide

Abstract

Brain-inspired computing emerged as a forefront technology to harness the growing amount of data generated in an increasingly connected society. The complex dynamics involving short- and long-term memory are key to the undisputed performance of biological neural networks. Here, we report on sub-µm-sized artificial synaptic weights exploiting a combination of a ferroelectric space charge effect and oxidation state modulation in the oxide channel of a ferroelectric field effect transistor. They lead to a quasi-continuous resistance tuning of the synapse by a factor of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>60</mml:mn></mml:math> and a fine-grained weight update of more than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>200</mml:mn></mml:math> resistance values. We leverage a fast, saturating ferroelectric effect and a slow, ionic drift and diffusion process to engineer a multi-timescale artificial synapse. Our device demonstrates an endurance of more than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow> <mml:mrow><mml:mn>10</mml:mn></mml:mrow> </mml:msup> </mml:math> cycles, a ferroelectric retention of more than <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>10</mml:mn></mml:math> years, and various types of volatility behavior on distinct timescales, making it well suited for neuromorphic and cognitive computing.