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.

Date Published: 28 July 2008
PDF: 12 pages
Proc. SPIE 7020, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV, 70200H (28 July 2008); doi: 10.1117/12.787092

Published in SPIE Proceedings Vol. 7020:
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy IV
William D. Duncan; Wayne S. Holland; Stafford Withington; Jonas Zmuidzinas, Editor(s)