Improved Facet and Edge Passivation in Near-Infrared III-V Colloidal Quantum Dot Photodetectors

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Lead-free III-V colloidal quantum dots (CQDs) show promise for near-infrared (NIR) and short-wave infrared (SWIR) photodetection.
• Effective surface passivation of larger CQDs is crucial for SWIR applications but remains a significant challenge.

Purpose of the Study:

• To develop an effective surface passivation strategy for large InAs CQDs.
• To enhance the anti-oxidation ability and stability of InAs CQDs for SWIR photodetection.

Main Methods:

• A mixed-halide passivation strategy was employed for large InAs CQDs.
• Density functional theory (DFT) simulations and facet characterization were used to analyze passivation effectiveness.
• Fabrication and testing of photodetectors operating at 1140 nm.

Main Results:

• The mixed-halide passivation doubled the anti-oxidation ability of InAs CQDs.
• Achieved a hole mobility of 0.03 cm²Vs⁻¹ and a T90 lifetime of 50 h.
• Developed InAs photodetectors with 75% external quantum efficiency (EQE) and a 10 ns response time at 1140 nm.

Conclusions:

• Mixed-halide passivation effectively addresses surface challenges in large InAs CQDs.
• This strategy significantly enhances photodetector performance and stability for SWIR applications.
• The findings pave the way for advanced lead-free CQD-based photodetector technologies.