Low energy switching of phase change materials using a 2D thermal boundary layer

Jing Ning*, Yunzheng Wang, Ting Yu Teo, Chung Che Huang, Ioannis Zeimpekis, Katrina Morgan, Siew Lang Teo, Daniel W. Hewak, Michel Bosman, Robert E. Simpson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


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.

Original languageEnglish
Pages (from-to)41225-41234
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number36
Early online date31 Aug 2022
Publication statusPublished - 14 Sept 2022

Bibliographical note

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.


  • 2D materials
  • low energy switching
  • phase change memory
  • thermal engineering
  • van der Waals interfaces

ASJC Scopus subject areas

  • General Materials Science


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