Ultrafast Carrier Dynamics in 2D NbTe2 Films: Implications for Photonic and Optoelectronic Devices.

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 and the peak amplitude of the transient reflectivity increases linearly with the pump power. The isotropic relaxation dynamics in NbTe₂ is also verified by performing polarization-resolved pump–probe measurements. These results provide 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. [ABSTRACT FROM AUTHOR]