Atomistic Understanding of 2D Monatomic Phase‐Change Material for Non‐Volatile Optical Applications
Advanced Science, vol. 13, pp. e13157
Abstract
Elemental antimony (Sb) is a promising material for phase-change memory, neuromorphic computing, and nanophotonic applications, because its compositional simplicity prevents phase segregation upon extensive programming. Scaling down the film thickness is a necessary step to prolong the amorphous-state lifetime. However, the optical properties of Sb are significantly altered as the thickness is reduced to a few nanometers, adding complexity to device optimization. In this work, an atomistic understanding of the thickness-dependent optical responses is provided in Sb thin films. As thickness decreases, both the extinction coefficient and optical contrast are reduced in the near-infrared spectrum, consistent with previous optical measurements. Such thickness dependence establishes a practical thickness limit of 2 nm, as predicted by coarse-grained device simulations. Bonding analysis reveals a fundamentally different behavior for amorphous and crystalline Sb upon downscaling, resulting in the reduction of optical contrast. Thin film experiments are also carried out to validate our predictions. The thickness-dependent optical trend is demonstrated by ellipsometric spectroscopy experiments, and the bottom thickness limit of 2 nm is confirmed by structural characterization experiments. Finally, it is shown that the greatly improved amorphous-phase stability of the 2 nm Sb thin film enables robust and reversible optical switching in a silicon-based waveguide device.
Authors 8
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Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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Wen Yan Zhou corresponding
Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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Forschungszentrum Jülich · RWTH Aachen University
Affiliation as printed
Institute of Physics IA RWTH Aachen University 52074 Aachen Germany
Peter Grünberg Institute (PGI 10) Forschungszentrum Jülich GmbH 52425 Jülich Germany
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Riccardo Mazzarello corresponding
Affiliation as printed
Department of Physics Sapienza University of Rome Rome 00185 Italy
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Wei Zhang corresponding
Affiliation as printed
Center for Alloy Innovation and Design (CAID) State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong University Xi'an 710049 China
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