Nb₅N₆ microbolometer for sensitive, fast-response, 2-µm detection

Area of Science:

• Materials Science
• Infrared Technology
• Nanotechnology

Background:

• Infrared detection is crucial for various applications, including thermal imaging and spectroscopy.
• Existing microbolometers often require cryogenic cooling or have limitations in sensitivity and response time.
• Development of room-temperature infrared detectors operating in the short-wave infrared (SWIR) range is highly desirable.

Purpose of the Study:

• To demonstrate room-temperature thermal detection at 2 µm using a novel Nb5N6 microbolometer.
• To evaluate the photothermal response and performance characteristics of Nb5N6 microbolometers.
• To explore a cost-effective technique for fabricating large-scale infrared focal plane arrays.

Main Methods:

• Fabrication and characterization of two types of Nb5N6 microbolometers.
• Suspension of Nb5N6 microwires to minimize thermal conductance.
• Measurement of optical voltage responsivity, noise equivalent power, and detectivity at 2 µm.
• Evaluation of response time for the microbolometer devices.

Main Results:

• Successful demonstration of room-temperature thermal detection at 2 µm with Nb5N6 microbolometers.
• Achieved a significant reduction in thermal conductance by a factor of 39 through device suspension.
• Measured optical voltage responsivity of 61.5 V/W.
• Obtained a noise equivalent power of 8.5 × 10⁻¹¹ W/√Hz and detectivity (D*) of 2.0 × 10⁷ cm√Hz /W.
• Demonstrated a fast response time of 0.17 ms for a 10 × 30-µm² device.

Conclusions:

• Nb5N6 is a promising material for room-temperature SWIR microbolometers.
• The suspended microwire design effectively enhances thermal isolation and device performance.
• This technology presents a simple, low-cost approach for scalable silicon-based focal plane array development for infrared detection.