Onto a double layer, which is made of a Si substrate ( ρ> 1000 Ω·cm ) and a SiO2 layer 100 nm thick
on top of it, a Nb5N6 thin film microbridge is deposited and integrated with an aluminum bow-tie
planar antenna. With a SiO2 air-bridge further fabricated underneath the microbridge and operated
at room temperature, such a combination behaves very well as a bolometer for detecting signals at
100 GHz, thanks to a temperature coefficient of resistance (TCR) as high as -0.7% K-1 of the Nb5N6 thin film. According to our estimations, the best attainable electrical responsivity of the bolometer is
about -400 V/W at a current bias of 0.4 mA. The electrical noise equivalent power (NEP) is 6.9x10-11 W/Hz1/2 for a modulation frequency at 300 Hz and 9.8x10-12 W/Hz1/2 for a modulation frequency
above 10 kHz respectively, which are better than those of commercial products (such as Golay cell
and Schottky diode detectors). A quasi-optical receiver based on such a bolometer is constructed and
measured.
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