Thermal conductivity and sound velocity measurements of plasma enhanced chemical vapor deposited a-SiC:H thin films

We report ultrafast optical measurements of the thermal conductivity and longitudinal sound velocity for a-SiC:H thin films deposited by plasma enhanced chemical vapor deposition (PECVD). Porous and non-porous films with mass densities ranging from 1.0–2.5 g/cm3 were obtained by intentionally varying the PECVD process conditions. The longitudinal sound velocities for these materials as determined by picosecond ultrasonics ranged from 2370 m/s to 10460 m/s, and the Young's modulus determined from the sound velocity measurements ranged from 5–200 GPa. Time domain thermoreflectance measurements determined the thermal conductivity to range from 0.0009 W/cmK to 0.042 W/cmK.