Shortwave Infrared Photodetection with oCVD Polythiophene

Area of Science:

• Materials Science
• Optoelectronics
• Semiconductor Physics

Background:

• Shortwave infrared (SWIR) photodetectors traditionally rely on compound semiconductors, necessitating high-temperature epitaxial growth and active cooling.
• Current research actively seeks novel technologies to overcome these fabrication and operational constraints for SWIR detection.

Purpose of the Study:

• To introduce a new method for fabricating room-temperature SWIR photodetectors.
• To demonstrate the potential of polymer-based systems for SWIR sensing applications.

Main Methods:

• Utilized oxidative chemical vapor deposition (oCVD) for the first time to create a polymer-based SWIR detector.
• Employed a novel window-based process for simplified fabrication of doped polythiophene sensors.
• Characterized the detector's performance, including dark resistance, noise limitations, and specific detectivity (D*).

Main Results:

• Achieved a room-temperature, vapor-phase deposited SWIR photoconductive detector with a unique tangled wire film morphology.
• Demonstrated detection of nW-level photons from a 500°C blackbody radiator, a rare capability for polymer systems.
• Reported a dark resistance of 8.97 kΩ, an external quantum efficiency product of 395%, and a specific detectivity (D*) of 10^6 Jones, with potential for 10^10 Jones.

Conclusions:

• The developed oCVD polymer-based SWIR detectors represent a significant advancement, overcoming limitations of traditional semiconductor photodetectors.
• These room-temperature detectors show promise for applications currently dominated by microbolometers and lead salt photoconductors.
• Further optimization, particularly in minimizing 1/f noise, could position these polymer-based detectors as competitive alternatives in the SWIR sensing market.