Ultrahigh-gain colloidal quantum dot infrared avalanche photodetectors

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Colloidal quantum dots (CQDs) offer potential for low-cost infrared (IR) photodetectors.
• Thermal noise in low-bandgap CQD materials currently limits IR detector performance.
• Photoinduced charge multiplication in CQDs is a key mechanism for enhanced sensitivity.

Purpose of the Study:

• To develop a novel CQD-based infrared photodetector architecture.
• To overcome thermal noise limitations in low-bandgap CQD photodetectors.
• To achieve high detectivity and explore single-photon detection capabilities.

Main Methods:

• Implementation of a kinetically pumped avalanche multiplication mechanism.
• Application of a strong electric field to a thick CQD layer (>540 nm).
• Optimization of CQD dot-to-dot distance (~4.1 nm) to balance impact ionization and electron hopping.

Main Results:

• Achieved a maximum multiplication gain of 85.
• Demonstrated a peak detectivity of 1.4 × 10^14 Jones at 940 nm.
• Successfully initiated kinetically pumped charge multiplication in CQDs.

Conclusions:

• The proposed architecture effectively utilizes kinetically pumped avalanche multiplication in CQDs.
• Optimized CQD photodetectors show significant potential for ultrahigh detectivity applications.
• This technology could enable advancements in single-photon detection.