Kapitza conductance of Bi/sapphire interface studied by depth- and time-resolved X-ray diffraction

We present Kapitza conductance measurements of the bismuth/sapphire interface using depth- and time-resolved X-ray diffraction, for Bi film thicknesses ranging from 65 to 284 nm. Our measurements provide complementary information about heat transport in the films; we directly observe the thinnest film to be uniformly heated within 1 ns, whereas the thickest film sustains a large near-surface temperature gradient for several ns. The deduced Kapitza conductance is 1950 W/cm2/K. This value is close to the theoretical prediction using the radiation limit.

► The first application of depth- and time-resolved XRD for thermal transport. ► We can separate the thermal conductivity from the Kapitza conductance. ► The extracted Kapitza conductance is close to the theoretical prediciton.