Thermal boundary conductance of transition metals on diamond

An experimental process that was used to obtain a direct measurement of Thermal Boundary Conductance (TBC) between a diamond substrate and several transition metals, deposited by sputtering, is described. Using Time-Domain ThermoReflectance (TDTR), the critical parameters, for a proper interpretation of the results, are evaluated to be the laser spot size and the thickness of the metallic thin films. Values of TBC between Cu, Cr, Nb, Mo, W and diamond are presented and vary between 30 and 280 MWm-2K-1. The adhesion of the layer to the substrate is seen to be critical to obtain a high TBC. Annealing in vacuum at temperatures up to 600°C does not significantly seem to change the results obtained. When diamond surface is oxygen plasma-treated for better adhesion, the TBC between Cr and diamond is measured to be 325 MWm-2K-1.This represents an 11-fold increase compared to untreated diamond.