  We have developed a transient thermoreflectance technique using picosecond
pulsed and cw laser to study thermal conductivity and interface conductance in
both thin-films and bulk materials. A real time-resolved system observes a
thermal transport along the cross-plane direction of the sample during a single
pulse excitation. The suggested TTR technique can measure thermal conductivity
in up to a few hundred nm of thin films with a reasonable uncertainty by
carefully selecting metal transducer thickness. In this paper, we examine
thermal conductivity in several substrates including Si, GaAs, Sapphire, and
Glass after depositing Au thin film as metal transducer and compare with
reported values to validate our technique. For further study on our method,
MoS2 thin-films with different thicknesses are prepared via exfoliating, and
their thermal conductivity are measured as average value of 3.4 W/mK. Compared
to TDTR technique, TTR is a simpler and inexpensive method to study
thermophysical properties and can also measure in-plane thermal property using
a grating imaging technique. TTR can be one of the available options for
observing thermal transport phenomena in both horizontal and vertical
directions with a simple and inexpensive preparation.
