YBCO microbolometer operating below T/sub c/: a modelization based on critical current-temperature dependence

Using careful measurements of the I-V curve of a YBCO thin-film microbridge under light irradiation at 780 nm and temperature close to 77 K, it is shown that the critical current versus temperature dependence is a good thermometer for estimating bolometric effects in the film. A novel dynamic voltage bias is introduced which directly gives the device current responsitivity and greatly reduces risks of thermal runaway. Detectivity is very low but it is predicted that a noise equivalent temperature of less than 10/sup -7/ K/ square root Hz would be achievable in a wide temperature range (10-80 K), which is an improvement over thermometry at the resistive transition.<>