  We report on the phonon and thermal properties of thin films of tantalum
diselenide (2H-TaSe2) obtained via the graphene-like mechanical exfoliation of
crystals grown by chemical vapor transport. The ratio of the intensities of the
Raman peak from the Si substrate and the E2g peak of TaSe2 presents a
convenient metric for quantifying film thickness. The temperature coefficients
for two main Raman peaks, A1g and E2g, are -0.013 and -0.0097 cm-1/oC,
respectively. The Raman optothermal measurements indicate that the room
temperature thermal conductivity in these films decreases from its bulk value
of ~16 W/mK to ~9 W/mK in 45-nm thick films. The measurement of electrical
resistivity of the field-effect devices with TaSe2 channels indicates that heat
conduction is dominated by acoustic phonons in these van der Waals films. The
scaling of thermal conductivity with the film thickness suggests that the
phonon scattering from the film boundaries is substantial despite the sharp
interfaces of the mechanically cleaved samples. These results are important for
understanding the thermal properties of thin films exfoliated from TaSe2 and
other metal dichalcogenides, as well as for evaluating self-heating effects in
devices made from such materials.
