Design and fabrication of superconducting transition edge sensor bolometers with background limited noise performance

We successfully designed and fabricated TES bolometers utilizing Al/Ti bilayer TESs as sensitive thermometers. To reduce the intrinsic noise level and tune the saturation power of a bolometer, the TES thermometer is placed on a suspended SiN platform which is thermally coupled to the heat bath by four long SiN beams with different geometries. The measurement results show that the detectors have background limited noise performance, with a low noise equivalent power (NEP) on the order of 10−17 W/Hz1/2 and have a saturation power of several tens pW at a bath temperature of 320 mK. These detectors are suitable for applications in ground-based astrophysics experiments by integrating absorbers for specific wavelengths.