Low energy switching of phase change materials using a 2D thermal boundary layer
Low energy switching of phase change materials using a 2D thermal boundary layer
The switchable optical and electrical properties of phase change materials (PCMs) are finding new applications beyond data storage in reconfigurable photonic devices. However, high power heat pulses are needed to melt-quench the material from crystalline to amorphous. This is especially true in silicon photonics, where the high thermal conductivity of the waveguide material makes heating the PCM energy inefficient. Here, we improve the energy efficiency of the laser-induced phase transitions by inserting a layer of two-dimensional (2D) material, either MoS2 or WS2, between the silica or silicon substrate and the PCM. The 2D material reduces the required laser power by at least 40% during the amorphization (RESET) process, depending on the substrate. Thermal simulations confirm that both MoS2 and WS2 2D layers act as a thermal barrier, which efficiently confines energy within the PCM layer. Remarkably, the thermal insulation effect of the 2D layer is equivalent to a ∼100 nm layer of SiO2. The high thermal boundary resistance induced by the van der Waals (vdW)-bonded layers limits the thermal diffusion through the layer interface. Hence, 2D materials with stable vdW interfaces can be used to improve the thermal efficiency of PCM-tuned Si photonic devices. Furthermore, our waveguide simulations show that the 2D layer does not affect the propagating mode in the Si waveguide; thus, this simple additional thin film produces a substantial energy efficiency improvement without degrading the optical performance of the waveguide. Our findings pave the way for energy-efficient laser-induced structural phase transitions in PCM-based reconfigurable photonic devices.
2D materials, low energy switching, phase change memory, thermal engineering, van der Waals interfaces
41225-41234
Ning, Jing
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Wang, Yunzheng
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Teo, Ting Yu
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Huang, Kevin Chung-Che
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Zeimpekis, Ioannis
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Morgan, Katrina
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Teo, Siew Lang
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Hewak, Daniel W.
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Bosman, Michel
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Simpson, Robert E.
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31 August 2022
Ning, Jing
dc9f1dfa-69c3-4ccc-8cc2-29d9252ff29e
Wang, Yunzheng
64696f3e-f5e0-4e1e-a52b-3870dda561cf
Teo, Ting Yu
8ce69bcf-c49e-48e2-bdfd-3f54b6bba83a
Huang, Kevin Chung-Che
825f7447-6d02-48f6-b95a-fa33da71f106
Zeimpekis, Ioannis
a2c354ec-3891-497c-adac-89b3a5d96af0
Morgan, Katrina
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Teo, Siew Lang
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Hewak, Daniel W.
87c80070-c101-4f7a-914f-4cc3131e3db0
Bosman, Michel
a800463c-0e3e-4745-a4f1-474d14097a75
Simpson, Robert E.
ea6c0d6d-2e92-4efd-92ed-c676d15b00f2
Ning, Jing, Wang, Yunzheng, Teo, Ting Yu, Huang, Kevin Chung-Che, Zeimpekis, Ioannis, Morgan, Katrina, Teo, Siew Lang, Hewak, Daniel W., Bosman, Michel and Simpson, Robert E.
(2022)
Low energy switching of phase change materials using a 2D thermal boundary layer.
ACS Applied Materials and Interfaces, 14 (36), .
(doi:10.1021/acsami.2c12936).
Abstract
The switchable optical and electrical properties of phase change materials (PCMs) are finding new applications beyond data storage in reconfigurable photonic devices. However, high power heat pulses are needed to melt-quench the material from crystalline to amorphous. This is especially true in silicon photonics, where the high thermal conductivity of the waveguide material makes heating the PCM energy inefficient. Here, we improve the energy efficiency of the laser-induced phase transitions by inserting a layer of two-dimensional (2D) material, either MoS2 or WS2, between the silica or silicon substrate and the PCM. The 2D material reduces the required laser power by at least 40% during the amorphization (RESET) process, depending on the substrate. Thermal simulations confirm that both MoS2 and WS2 2D layers act as a thermal barrier, which efficiently confines energy within the PCM layer. Remarkably, the thermal insulation effect of the 2D layer is equivalent to a ∼100 nm layer of SiO2. The high thermal boundary resistance induced by the van der Waals (vdW)-bonded layers limits the thermal diffusion through the layer interface. Hence, 2D materials with stable vdW interfaces can be used to improve the thermal efficiency of PCM-tuned Si photonic devices. Furthermore, our waveguide simulations show that the 2D layer does not affect the propagating mode in the Si waveguide; thus, this simple additional thin film produces a substantial energy efficiency improvement without degrading the optical performance of the waveguide. Our findings pave the way for energy-efficient laser-induced structural phase transitions in PCM-based reconfigurable photonic devices.
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Accepted/In Press date: 18 August 2022
e-pub ahead of print date: 31 August 2022
Published date: 31 August 2022
Additional Information:
Funding Information:
The SUTD research was funded by a Singapore MoE Project “Electric-field induced transitions in chalcogenide monolayers and superlattices”, grant MoE 2017-T2-1-161 and an A*STAR AME project: ”Nanospatial Light Modulators (NSLM)”, A18A7b0058. The 2D materials work was supported by the UK’s Engineering and Physical Sciences Research Council through the Future Photonics Manufacturing Hub (EPSRC EP/N00762 X/1), the Chalcogenide Photonic Technologies (EPSRC EP/M008487/1), and ChAMP–Chalcogenide Advanced Manufacturing Partnership (EPSRC EP/G060363/1). J.N. is grateful for her MoE PhD scholarship.
Publisher Copyright:
© 2022 American Chemical Society.
Keywords:
2D materials, low energy switching, phase change memory, thermal engineering, van der Waals interfaces
Identifiers
Local EPrints ID: 469862
URI: http://eprints.soton.ac.uk/id/eprint/469862
ISSN: 1944-8244
PURE UUID: 675b4df7-340b-483c-b873-490871e813d1
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Date deposited: 27 Sep 2022 16:41
Last modified: 12 Nov 2024 05:02
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Contributors
Author:
Jing Ning
Author:
Yunzheng Wang
Author:
Ting Yu Teo
Author:
Kevin Chung-Che Huang
Author:
Katrina Morgan
Author:
Siew Lang Teo
Author:
Michel Bosman
Author:
Robert E. Simpson
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