Bozorg-Grayeli, E., Sood, A., Asheghi, M., Gambin, V., Sandhu, R., Feygelson, T.I., Pate, B.B., Hobart, K., and Goodson, K.E., 2013, “Thermal Conduction Inhomogeneity of Nanocrystalline Diamond Films by Dual-Side Thermoreflectance,” Applied Physics Letters, Vol. 102, 111907.
Thin diamond films of thickness near 1 micrometer can have highly nonuniform thermal conductivities owing to spatially varying disorder associated with nucleation and grain coalescence. Here, we examine the nonuniformity for nanocrystalline chemical vapor deposited diamond films of thickness 0.5, 1.0, and 5.6 lm using picosecond thermoreflectance from both the top and bottom diamond surfaces, enabled by etching a window in the silicon substrate. The extracted local thermal conductivities vary from less than 100W/mK to more than 1300W/mK and suggest that the most defective material is confined to within 1 micrometer of the growth surface.