What Has Been Achieved:
The mechanism of energy dissipation in 2D metal heterostructures was determined using transient absorption spectroscopy, which involves contributions from the various components of the heterostructure on sub-picosecond, picosecond, and 10s of picosecond timescales. The rates of relaxation are dependent on the structure of the 2Dmetal, with Ga/In alloys exhibiting faster rates of electron-phonon scattering than In or Ga alone. Correlative nonlinear optical microscopy and electron microscopy revealed increased structural disorder in the Ga/In alloy, explaining the faster relaxation.
Importance of the Achievement:
While the energy dissipation dynamics bulk coinage metals have been extensively studied, the effects of 2D confinement on metals has not been understood. This work reveals the impact that atomic-level structural disorder has on the dynamics of 2D metal heterostructures, and suggests avenues for controlling energy dissipation through alloying. Additionally, graphene-metal charge transfer was resolved in these systems, which could reduce thermal fouling in graphene-based technologies.
Unique Feature(s) of the MIP that Enabled this Achievement:
The synthesis of 2D-polar metal heterostructures, which represent an attractive system for studying 2D metal dynamics due to their large lateral dimensions and air stability, was enabled by the 2DCC
Megan A. Steves, Siavash Rajabpour, Ke Wang, Chengye Dong, Wen He, Su Ying Quek, Joshua A. Robinson, and Kenneth L. Knappenberger Jr., ACS Nano 15, 11, 17780 (2021). DOI:10.1021/acsnano.1c05944
This work was supported by a grant from the Air Force Office of Scientific Research (FA-9550-18-1-0347 and FA9550-19-1-0295) and by the National Science Foundation Graduate Research Fellowship Program under grant no. DGE1255832. This work was also supported by the National Science Foundation under award number CHE-1807999, DMR-2011839, and cooperative agreement DMR-1539916. Funding was also provided by the Singapore National Research Foundation, Prime Minister’s Office, under its medium-sized center program. Calculations were performed on the NUS Graphene Research Centre cluster and National Supercomputing Centre Singapore (NSCC).
Credits/Names: Megan A. Steves, Siavash Rajabpour, Ke Wang, Chengye Dong, Wen He, Su Ying Quek, Joshua A. Robinson, and Kenneth L. Knappenberger Jr.
Download PDF Version: 1539916_2DCCMIP_2022_Phonon Scattering Rates in 2-D Polar Metal Heterostructures.pdf
Year of Research Highlight: 2021
Select a Highlight Type: In-House Research Highlight