Orientation independent heat transport characteristics of diamond/copper interface with ion beam bombardment

Owing to high thermal conductivity (k) and appropriate coefficient of thermal expansion (CTE), Diamond/copper (Dia/Cu) composites have attracted extensive attention as advanced thermal management materials, but also suffered with low thermal boundary conductance (G). This is because complex energy carrier behaviors at metal/nonmetal interfaces. Although conventional carbide forming interlayers may serve as acoustic matching bridge, crystallographic orientation is still critical to influence heat transport characteristics of Dia/Cu interface. In this work, both theoretical calculations and time-domain thermoreflectance (TDTR) results revealed two distinct G of (100) and (111) Dia/Cu interfaces. We then applied an easy-controlled ion-beam bombardment technique to reduce the orientation dependent G, and two different trends are observed with ion-bombardment time (t): (1) when t < 30 min, G increases with increasing t; (2) when t > 30 min, G decreases with increasing t. Our microstructural and surface potential analysis suggests sp(3)-to-sp(2) hybridization and formation of nanoscale amorphous carbon (a-C) layer at the diamond surface. The coupling between electrons in Cu and a-C provides an additional heat transport pathway, however, the interfacial defect scattering becomes dominant when continuously increasing ion-bombardment time. The present findings may provide more insight to understand the orientation dependent heat transport mechanisms at metal/nonmetal interfaces. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

The study investigates the thermal boundary conductance of Dia/Cu interfaces with different crystallographic orientations. By applying ion-beam bombardment, the orientation dependent conductance is reduced, revealing contrasting trends in conductance with ion-bombardment time. The findings shed light on the heat transport mechanisms at metal/nonmetal interfaces.