To identify superior thermal contacts to graphene,
we implement a high-throughput methodology that systematically
explores the Ni−Pd alloy composition spectrum and the effect of
Cr adhesion layer thickness on thermal interface conductance with
monolayer graphene. Frequency domain thermoreflectance measurements
of two independently prepared Ni−Pd/Cr/graphene/
SiO2 samples identify a maximum metal/graphene/SiO2 junction
thermal interface conductance of 114 ± (39, 25) MW/m2 K and
113 ± (33, 22) MW/m2 K at ∼10 at. % Pd in Ninearly double
the highest reported value for pure metals and 3 times that of pure
Ni or Pd. The presence of Cr, at any thickness, suppresses this
maximum. Although the origin of the peak is unresolved, we find
that it correlates with a region of the Ni−Pd phase diagram that
exhibits a miscibility gap. Cross-sectional imaging by high-resolution transmission electron microscopy identifies striations in the
alloy at this particular composition, consistent with separation into multiple phases. Through this work, we draw attention to alloys
in the search for better contacts to two-dimensional materials for next-generation devices.
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Enhancing Thermal Interface Conductance to Graphene Using Ni-Pd Alloy Contacts
To identify superior thermal contacts to graphene we implement a high throughput methodology that systematically explores the Ni-Pd alloy composition spectrum and the effect of Cr adhesion layer thickness on the thermal interface conductance with monolayer CVD graphene. Frequency domain thermoreflectance measurements of two independently prepared Ni- Pd/Cr/graphene/SiO2 samples both identify a maximum in the metal/graphene/SiO2 junction thermal interface conductance of 114± (39, 25) MW/m2K and 113± (33, 22) MW/m2K at ~10 atomic percent Pd in Ni—nearly double the highest reported value for pure metals and three times that of pure Ni or Pd. The presence of Cr, at any thickness, suppresses this maximum. Although the origin of the peak is unresolved, we find that it correlates to a region of the Ni-Pd phase diagram that exhibits a miscibility gap. Cross sectional imaging by high resolution transmission electron microscopy identifies striations in the alloy at this particular composition, consistent with separation into multiple phases. Through this work, we draw attention to alloys in the search for better contacts to 2D materials for next generation devices.
more »
« less
- NSF-PAR ID:
- 10169663
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- ISSN:
- 1944-8244
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acsami.0c06953
