High-Performance and Stable HgTe Colloidal Quantum Dot Photodiodes Enabled by Hybrid Passivation

Area of Science:

• Materials Science
• Nanotechnology
• Quantum Dot Technology

Background:

• Mercury telluride (HgTe) colloidal quantum dots (CQDs) are promising for low-cost infrared imagers.
• Current HgTe detectors face challenges in performance and stability.
• ZnO/HgTe/ZnTe double heterojunctions enable photovoltaic mode operation.

Purpose of the Study:

• To improve the performance and stability of HgTe CQD infrared detectors.
• To develop a novel passivation strategy for HgTe CQDs.
• To enable reliable integration of HgTe CQD detectors with readout circuits.

Main Methods:

• A hybrid passivation strategy using methylammonium iodide (MAI) and HgI2 was employed.
• This method generates X-type HgI3- ligands for surface passivation.
• HgTe CQD detectors were fabricated and characterized, including integration with thin-film transistor (TFT) readout circuits.

Main Results:

• Hybrid passivated HgTe CQDs showed enhanced colloidal stability and surface passivation.
• The photodetector achieved 66.8% external quantum efficiency (EQE) at 1620 nm.
• Specific detectivity reached 1.45 × 10^12 Jones with a dark current density of 185 nA/cm^2.
• Enhanced detector stability was confirmed at single-pixel and array levels.

Conclusions:

• The hybrid passivation strategy effectively enhances HgTe CQD detector performance and stability.
• This approach offers a viable solution for next-generation infrared imaging applications.
• The improved detectors are suitable for integration into larger imaging arrays.