High-Performance Ta₂NiSe₅-Based Broadband Photodetectors toward Self-Powered and Polarization-Sensitive Detection

Area of Science:

• Materials Science
• Condensed Matter Physics
• Optoelectronics

Background:

• Two-dimensional (2D) tantalum selenide (Ta₂NiSe₅) is a promising broadband optoelectronic material due to its narrow bandgap, high carrier mobility, and stability.
• Existing Ta₂NiSe₅ heterostructures show high-performance detection under bias, but self-powered polarization-sensitive detection, especially under near-infrared (NIR) illumination, remains underexplored.

Purpose of the Study:

• Investigate the self-powered photoresponse and polarization-sensitive capabilities of novel 2D Ta₂NiSe₅-based heterojunctions.
• Evaluate Ta₂NiSe₅/MoS₂, Ta₂NiSe₅/MoSe₂, and Ta₂NiSe₅/MoSSe heterostructures for self-powered broadband detection.
• Demonstrate the potential for high-performance, self-powered, polarization-sensitive photodetectors.

Main Methods:

• Fabrication and characterization of Ta₂NiSe₅/MoS₂, Ta₂NiSe₅/MoSe₂, and Ta₂NiSe₅/MoSSe heterostructures.
• Measurement of photoresponse across ultraviolet to near-infrared spectrum under self-powered conditions.
• Assessment of polarization sensitivity, responsivity, specific detectivity, rectification ratio, on/off ratio, and dark current.

Main Results:

• The Ta₂NiSe₅/MoSSe heterostructure exhibits superior self-powered broadband polarization-sensitive detection from UV to NIR.
• Achieved high performance metrics: responsivity of 238 mA/W, specific detectivity of 2.73 × 10¹² Jones, rectification and on/off ratios of ~10⁵, and ultra-low dark current of 10^-14 A.
• Demonstrated significant polarization sensitivity (2.3 at 750 nm) attributed to the in-plane anisotropy of Ta₂NiSe₅.

Conclusions:

• Ta₂NiSe₅/MoSSe heterostructures are highly effective for self-powered broadband polarization-sensitive photodetection.
• The observed performance is linked to a strong built-in electric field and reduced contact resistance.
• This research provides a pathway for developing advanced self-powered and polarization-sensitive photodetectors.