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Progress on background-limited membrane-isolated TES bolometers for far-IR/submillimeter spectroscopy

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2006

Year

Abstract

To determine the lowest attainable phonon noise equivalent power (NEP) for membrane-isolation bolometers, we fabricated and measured the thermal conductance of suspended Si<sub>3</sub>N<sub>4</sub> beams with different geometries via a noise thermometry technique. We measured beam cross-sectional areas ranging from 0.35 × 0.5 <i>&#956;</i>m<sup>2</sup> to 135 × 1.0 <i>&#956;</i>m<sup>2</sup> and beam lengths ranging from 700 <i>&#956;</i>m to 8300 <i>&#956;</i>m. The measurements directly imply that membrane-isolation bolometers are capable of reaching a phonon noise equivalent power (NEP) of 4×10<sup>-20</sup> W/Hz<sup>1/2</sup>. This NEP is adequate for the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) proposed for the Japanese SPICA observatory, and adequate for NASA's SAFIR observatory, a 10-meter, 4 K telescope to be deployed at L2. Further, we measured the heat capacity of a suspended Si<sub>3</sub>N<sub>4</sub> membrane and show how this result implies that one can make membrane-isolation bolometers with a response time which is fast enough for BLISS.