A Distributed TES Model for Designing Low Noise
Bolometers Approaching SAFARI Instrument Requirements

P. Khosropanah^1* , R.A. Hijmering¹ , M. Ridder¹ ,
M.A. Lindeman¹, L. Gottardi¹ , M. Bruijn¹ , J. van der Kuur¹ , 
P.A.J. de Korte¹ , J.R. Gao1,² , H. Hoevers¹

¹SRON Netherlands Institute for Space Research, Sorbonnelaan
2, 3584 CA Utrecht, The Netherlands
²Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg
1, 2628 CJ Delft, The Netherlands

Abstract - Transition edge sensors (TES) are the chosen detector technology for the SAFARI imaging spectrometer on the SPICA telescope. The TES are required to have an NEP of 2-3×10⁻¹⁹ W/√Hz to take full advantage of the cooled mirror. SRON has developed TiAu TES bolometers for the short wavelength band (30-60 μm). The TES are on SiN membranes, in which long and narrow legs act as thermal links between the TES and the bath. We present a distributed model that accounts for the heat conductance and the heat capacity in the long legs that provides a guideline for designing low noise detectors. We report our latest results that include a measured dark NEP of 4.2×10⁻¹⁹ W/√Hz and a saturation power of about 10 ƒW.
PACS numbers: 85.25.Pb, 95.85.Gn

Submitted to ESNF July 28, 2011; accepted October 06, 2011.  Reference ST274, Category 4
Published in  Journal of Low Temperature Physics 167, Numbers 3-4, 188-194 (2012)