  As wide bandgap electronic devices have continued to advance in both size
reduction and power handling capabilities, heat dissipation has become a
significant concern. To mitigate this, chemical vapor deposited (CVD) diamond
has been demonstrated as an effective solution for thermal management of these
devices by directly growing onto the transistor substrate. A key aspect of
power and radio frequency (RF) electronic devices involves transient switching
behavior, which highlights the importance of understanding the temperature
dependence of the heat capacity and thermal conductivity when modeling and
predicting device electrothermal response. Due to the complicated
microstructure near the interface between CVD diamond and electronics, it is
difficult to measure both properties simultaneously. In this work, we use time
domain thermoreflectance (TDTR) to simultaneously measure the in plane thermal
conductivity and heat capacity of a 1 um thick CVD diamond film, and also use
the pump as an effective heater to perform temperature dependent measurements.
The results show that the in plane thermal conductivity varied slightly with an
average of 103 W per meter per K over a temperature range of 302 to 327 K,
while the specific heat capacity has a strong temperature dependence over the
same range and matches with heat capacity data of natural diamond in
literature.
