Ultrafast Carrier Dynamics in 2D NbTe2 Thin Films

Abstract

<p>As one of the representatives of emerging metallic transition metal dichalcogenides, niobium ditelluride (NbTe<sub>2</sub>) has attracted intensive interest recently due to its distorted lattice structure and unique physical properties. Here, we report on the ultrafast carrier dynamics in NbTe<sub>2</sub> 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 NbTe<sub>2</sub> 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 NbTe<sub>2</sub> 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 NbTe<sub>2</sub> and will pave the way for its applications to photonic and optoelectronic devices.</p>