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

Abstract

Room-temperature thermal detection at a wavelength of 2 µm in the short-wave infrared range (1.7-3 µm) was demonstrated for the first time using a NbN microbolometer. The photothermal responses of two types of NbN microbolometers were evaluated. By suspending NbN microwires in the air above the substrate, a reduction in thermal conductance of the device by a factor of 39 was achieved. The measured optical voltage responsivity R of the NbN microbolometer reached the value of 61.5 V/W. A noise equivalent power of 8.5 × 10 W/√Hz (at 1 kHz) and a detectivity D* = 2.0 × 10 cm√Hz /W with a typical response time as small as 0.17 ms was obtained at a wavelength of 2 µm for a 10 × 30-µm device. The performance could be improved further by optimizing the design and operating parameters. This study revealed a simple low-cost technique to develop a large-scale focal plane array in silicon for infrared detection.

Electrically addressable integrated intelligent terahertz metasurface

“…Figure 3D shows the relationship between the response voltage and the modulation frequency when the subarray is biased with 4 mA at 60°C. We fitted the experimental data as a function of the modulation frequency to obtain the response time ( 46 ). The best fit corresponds to a thermal relaxation time of 24 μs.…”

Terahertz communication: detection and signal processing

“…Secondly, the prerequisite for continuous temperature calibration during bolometer operation can present challenges in specific field applications [52]. Tu et al [53] have designed and fabrication a microbolometer based on Nb 5 N 6 material, which achieved up to 61.5 V W −1 maximum voltage responsivity with 8.5×10 −11 W Hz −1/2 NEP value. Aji et al [54] combined the microbolometer with another dipole antenna, which performs up to 530 V W −1 responsivity with 42 pW Hz −1/2 NEP value within the regime of 0-1 THz.…”

Recent advances in infrared imagers: toward thermodynamic and quantum limits of photon sensitivity

“…Since thermal noise spectrum at 300 K is peaked around 10 µm wavelength, the detection of much shorter wavelength with microbolometers is flawed by low signal-to-noise ratio resulting from high absorption of the thermal noise at longer wavelengths. As a result, the performance metrics of microbolometers typically lay orders of magnitude below those of photon detectors in the SWIR band [84,85].…”

“…On the other hand, this sensitivity improvement will likely come at the price of a reduced quantum efficiency, due to poor coupling of light into such a small volume. Charge compression and transfer, allowing the integration of a large-volume photon absorber with a small amplification region, offers a viable solution to mitigate this drawback [85]. However, its effects are limited by parasitic capacitance and surface effects.…”