The use of RuO2 resistors as broadband low-temperature radiation sensors

The possibility of using commercial RuO2 planar resistors as low-temperature radiation sensors was investigated. At temperatures of 0.08-0.1 K, their sensitivity to blackbody radiation at temperatures of 5-40 K was about 2-3 pW. The radiation absorption coefficient was < 10%. The response is a linear function of the radiation power, thus indicating that the detector band is no narrower than 0.5-2.5 THz. The rise time of an output signal without feedback-assisted temperature stabilization was similar to 12 s owing to an unexpectedly high thermal capacity of the resistor.