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

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 Nb₅N₆ microbolometer. The photothermal responses of two types of Nb₅N₆ microbolometers were evaluated. By suspending Nb₅N₆ 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_O of the Nb₅N₆ microbolometer reached the value of 61.5 V/W. A noise equivalent power of 8.5 × 10^-11 W/√Hz (at 1 kHz) and a detectivity D* = 2.0 × 10⁷ 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-µm² 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.