We present the experimental results and a bolometer model of the voltage-biased superconducting bolometer
on the low stress silicon nitride (Si3N4) membrane, developed in collaboration between the Max-Planck-Institut
fur Radioastronomie (MPIfR), Bonn and the Institute for Photonic Technology (IPHT), Jena, Germany. The
superconducting thermistor, deposited on the low stress silicon nitride membrane, is a bilayer of gold-palladium
and molybdenum and is designed for a transition temperature of 450 mK. Bolometers for the 1.2 mm atmospheric
window were designed, built and tested. The thermal conductance of the bolometer is tuned by structuring the
silicon nitride membrane into spider-like geometries. The incident radiation is absorbed by crossed dipoles
made from gold-palladium alloy with a surface resistance of 10 Ω/square. Using the COSMOS finite element analysis
package, the thermal conductance is obtained for the bolometers of different geometries. FEA simulations showed
that the deposition of a gold ring around the absorbing area could increase the sensitivity of the bolometer.
Therefore, a gold ring is deposited around the center absorbing patch of the silicon nitride membrane. For the
bolometer with a gold ring, the measured NEP is 1.7 X (see manuscript for formula)
Hz and the time constant is in the range
between 1.4 and 2 ms.