In-Grain Ferroelectric Switching in Sub-5 nm Thin AlScN Films at 1 V

Georg Schönweger; Niklas Wolff; Md Redwanul Islam; Maike Gremmel; Adrian Petraru; Lorenz Kienle; Hermann Kohlstedt; Simon Fichtner

arXiv · 2304.02909

In-Grain Ferroelectric Switching in Sub-5 nm Thin AlScN Films at 1 V

Georg Schönweger·Niklas Wolff·Md Redwanul Islam·Maike Gremmel·Adrian Petraru·Lorenz Kienle·Hermann Kohlstedt·Simon Fichtner

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Abstract

Analog switching in ferroelectric devices promises neuromorphic computing with highest energy efficiency, if limited device scalability can be overcome. To contribute to a solution, we report on the ferroelectric switching characteristics of sub-5 nm thin Al$_{0.74}$Sc$_{0.26}$N films grown on Pt/Ti/SiO2/Si and epitaxial Pt/GaN/sapphire templates by sputter-deposition. In this context, we focus on the following major achievements compared to previously available wurtzite-type ferroelectrics: 1) Record low switching voltages down to 1 V are achieved, which is in a range that can be supplied by standard on-chip voltage sources. 2) Compared to the previously investigated deposition of thinnest Al$_{1-x}$Sc$_x$N films on epitaxial templates, a significantly larger coercive field to breakdown field ratio is observed for Al$_{0.74}$Sc$_{0.26}$N films grown on silicon substrates, the technologically most relevant substrate-type. 3) The formation of true ferroelectric domains in wurtzite-type materials is for the first time demonstrated on the atomic scale by scanning transmission electron microscopy investigations of a sub-5 nm thin partially switched film. The direct observation of inversion domain boundaries within single nm-sized grains supports the theory of a gradual domain-wall motion limited switching process in wurtzite-type ferroelectrics. Ultimately, this should enable the analog switching necessary for mimicking neuromorphic concepts also in highly scaled devices.

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Georg Schönweger, Niklas Wolff, Md Redwanul Islam, Maike Gremmel, Adrian Petraru, Lorenz Kienle, Hermann Kohlstedt, Simon Fichtner. 2023-04-06. In-Grain Ferroelectric Switching in Sub-5 nm Thin AlScN Films at 1 V. https://arxiv.org/abs/2304.02909

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