Probing Carrier Dynamics in Large-Scale MBE-Grown PtSe₂ Films by Terahertz Spectroscopy.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Atomically thin platinum diselenide (PtSe2) films possess tunable electronic structures and high carrier mobility, making them promising for electronics, spintronics, and photodetectors.
• Understanding the phase transitions and carrier dynamics in PtSe2 is crucial for optimizing its device performance.

Purpose of the Study:

• To investigate the layer-dependent semiconducting-to-metallic phase transition in large-scale PtSe2 films.
• To study the intrinsic carrier dynamics and photoexcited carrier transport using terahertz (THz) spectroscopy.
• To demonstrate large-scale THz-based electrical property mapping of transition metal dichalcogenide films.

Main Methods:

• Growth of large-scale PtSe2 films via molecular beam epitaxy.
• Characterization of film uniformity using spatially and frequency-resolved THz-based sheet conductivity mapping.
• Investigation of photoexcited carrier dynamics and intergrain transport with optical-pump-THz-probe spectroscopy.

Main Results:

• Observation of a layer-dependent semiconducting-to-metallic phase transition in PtSe2 films.
• Spatially resolved THz conductivity mapping demonstrated the uniformity of large-scale PtSe2 films.
• Optical-pump-THz-probe technique provided insights into photoexcited carrier transport dynamics.

Conclusions:

• Terahertz spectroscopy is a powerful noncontact technique for characterizing the spatial and temporal properties of PtSe2 films.
• The study demonstrates the potential of THz-based methods for large-scale electrical mapping of transition metal dichalcogenides.
• Understanding carrier dynamics is key to harnessing PtSe2 for advanced electronic and optoelectronic applications.