Interfacial engineering in WS₂/CdSe heterostructures for high-performance broadband photodetection

Area of Science:

• Materials Science
• Nanotechnology
• Condensed Matter Physics

Background:

• Two-dimensional transition metal dichalcogenides (TMDs) exhibit limited light absorption at atomic thicknesses, hindering optoelectronic device performance.
• Weak light absorption and dark current are critical challenges for ultrathin 2D materials in optoelectronics.

Purpose of the Study:

• To enhance the optoelectronic performance of WS₂/CdSe heterostructures by integrating gold nanoparticles (Au NPs).
• To investigate the synergistic effects of plasmonic enhancement and Schottky contact formation for improved light absorption and suppressed dark current.

Main Methods:

• Fabrication of WS₂/CdSe heterostructures with precisely engineered van der Waals interfaces.
• Integration of gold nanoparticles (Au NPs) at the WS₂/CdSe interface to create plasmonic hotspots and Schottky contacts.
• Characterization using scanning Kelvin probe force microscopy (SKPFM) and finite-element simulations to verify band alignment and plasmonic effects.

Main Results:

• Au NPs significantly boosted light absorption and photocurrent generation through localized electric field amplification via surface plasmon resonance.
• Schottky contacts formed by Au NPs established electron depletion zones, effectively suppressing dark current.
• Achieved a 339.9× improvement in light-to-dark current ratio and a 119.9× increase in responsivity.

Conclusions:

• Interfacial engineering with Au NPs is a highly effective strategy for developing high-performance 2D optoelectronic devices.
• The synergistic plasmonic and Schottky effects offer a universal approach to overcome fundamental limitations in ultrathin optoelectronic materials.