Si-HgTe Quantum Dot Visible-Infrared Photodetector.

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Silicon photodetectors are cost-effective but limited to visible and near-infrared wavelengths due to their band gap.
• Expanding detection range is crucial for advanced optical sensing applications.

Purpose of the Study:

• To develop a broadband photodetector by extending silicon's spectral response into the short-wave infrared (SWIR) range.
• To integrate mercury telluride colloidal quantum dots (CQDs) with silicon photodiodes for enhanced spectral coverage.

Main Methods:

• Fabrication of a stacked photodetector comprising a HgTe CQD photodiode and a silicon PIN photodiode in series.
• Characterization of the device's spectral response, photocurrent, response speed, and detectivity at room temperature.
• Demonstration of device application using a homemade trans-impedance amplifier (TIA) circuit.

Main Results:

• The stacked detector exhibits a broad spectral response from 430 nm to 2800 nm (visible to SWIR) at room temperature.
• Achieved photocurrents of 112.5 μA (tungsten lamp) and 1.24 μA (blackbody) at zero bias.
• Demonstrated a fast response speed of 1.65 μs with high detectivities: D* = 1.01 × 10¹¹ Jones (visible) and D* = 2.66 × 10¹⁰ Jones (SWIR).

Conclusions:

• The stacked HgTe CQD/Si photodetector successfully extends detection capabilities to the SWIR range.
• The device offers excellent performance metrics, including broad spectral coverage, high photocurrent, fast response, and high detectivity.
• The demonstrated TIA circuit integration highlights the practical applicability of this broadband photodetector for various sensing tasks.