  Titanium trisulfide (TiS3) has recently attracted the interest of the 2D
community as it presents a direct bandgap of ~1.0 eV, shows remarkable
photoresponse, and has a predicted carrier mobility up to 10000 cm2V-1 s-1.
However, a study of the vibrational properties of TiS3, relevant to
understanding the electron-phonon interaction which can be the main mechanism
limiting the charge carrier mobility, is still lacking. In this work, we take
the first steps to study the vibrational properties of TiS3 through temperature
dependent Raman spectroscopy measurements of TiS3 nanoribbons and nanosheets.
Our investigation shows that all the Raman modes linearly soften (red shift) as
the temperature increases from 88 K to 570 K, due to the anharmonic vibrations
of the lattice which also includes contributions from the lattice thermal
expansion. This softening with the temperature of the TiS3 modes is more
pronounced than that observed in other 2D semiconductors such as MoS2, MoSe2,
WSe2 or black phosphorus (BP). This marked temperature dependence of the Raman
could be exploited to determine the temperature of TiS3 nanodevices by using
Raman spectroscopy as a non-invasive and local thermal probe. Interestingly,
the TiS3 nanosheets show a stronger temperature dependence of the Raman modes
than the nanoribbons, which we attribute to a lower interlayer coupling in the
nanosheets.
