Abstract
As one of the representatives of emerging metallic transition metal
dichalcogenides, niobium ditelluride (NbTe2) has
attracted intensive interest recently due to its distorted lattice
structure and unique physical properties. Here, we report on the
ultrafast carrier dynamics in NbTe2 measured using
time-resolved pump-probe transient reflection spectroscopy. A
thickness-dependent carrier relaxation time is observed, exhibiting a
clear increase in the fast and slow carrier decay rates for thin
NbTe2 flakes. In addition, pump power dependent
measurements indicate that the carrier relaxation rates are
power-independent, with the peak amplitude of the transient reflectivity
increasing linearly with pump power. Isotropic relaxation dynamics in
NbTe2 is also verified by performing
polarization-resolved pump-probe measurements. These results provide an
insight into the light-matter interactions and charge carrier dynamics
in NbTe2 and will pave the way for its applications to
photonic and optoelectronic devices.