Scaling Short-Wave Infrared Detector Pixels to Subwavelength Dimensions.

Area of Science:

• Optoelectronics
• Materials Science
• Nanotechnology

Background:

• Pixel miniaturization is key for high-resolution short-wave infrared (SWIR) imaging in applications like remote sensing.
• Conventional photodiode technologies face limitations in pixel size (around 10 µm) for SWIR detection.
• Systematic studies on the limits of SWIR pixel miniaturization are scarce.

Purpose of the Study:

• To investigate the pixel scaling behavior of carbon nanotube (CNT) film heterojunction-gated field-effect transistor (HGFET) detectors.
• To demonstrate the feasibility and performance enhancements of subwavelength pixel SWIR detectors.
• To explore the potential of CNT HGFETs for next-generation SWIR imaging.

Main Methods:

• Fabrication and characterization of CNT film HGFET detectors with varying pixel sizes, from 5.5 µm down to 1.0 µm.
• Evaluation of key performance indicators, including specific detectivity and response speed, at 1300 nm.
• Demonstration of a subwavelength pixel detector with a pitch of 0.65λ (approximately 1.0 µm).

Main Results:

• Performance indicators, specifically specific detectivity and response speed, consistently improved as pixel size decreased.
• A subwavelength pixel HGFET detector (∼1.0 µm) achieved a record specific detectivity >10^15 cm·Hz^1/2·W^-1 at 1300 nm.
• The detector exhibited fast rise/fall times of 132/148 µs, indicating rapid signal processing.

Conclusions:

• Subwavelength pixel CNT HGFET detectors offer improved performance and feasibility for SWIR imaging.
• These detectors are compatible with silicon-based readout circuits, enabling scalable and cost-effective solutions.
• CNT HGFET arrays represent a promising platform for advancing high-resolution SWIR imaging systems.