Tunable Photoresponse in a Two-Dimensional Superconducting Heterostructure.

Area of Science:

• Condensed matter physics
• Materials science
• Nanotechnology

Background:

• Photo-induced superconducting transitions are vital for studying correlated electronic systems and broadband photodetection.
• Conventional superconductors exhibit photoresponse insensitive to electrostatic doping due to high carrier density, limiting tunable optoelectronic device applications.

Purpose of the Study:

• To demonstrate gate voltage modulation of photoresponsivity in a two-dimensional niobium diselenide-graphene heterojunction.
• To explore the underlying mechanism of gate-controlled photoresponse.
• To investigate the potential for tunable superconducting photodetectors.

Main Methods:

• Fabrication of a two-dimensional niobium diselenide-graphene heterojunction.
• Measurement of photoresponsivity under varying gate voltages.
• Temperature and laser power-dependent characterization of photoresponse.
• Spatially-resolved photocurrent mapping.

Main Results:

• Gate voltage modulation of photoresponsivity was achieved in the NbSe2-graphene heterojunction.
• The superconducting critical current was found to depend on gate-induced hot carrier generation in graphene via Joule heating.
• Shifts in the magnitude and peak position of photoresponsivity spectra were observed with changing gate voltage.
• Inhomogeneous superconductivity was detected across the junction area.

Conclusions:

• The study presents a novel platform for developing tunable superconducting photodetectors.
• Photoresponse can serve as a powerful tool for investigating local electronic properties and phase transitions in low-dimensional superconducting systems.
• Gate-controlled hot carrier generation in graphene influences the superconducting properties of NbSe2.