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Proceedings Paper

Low-noise transition edge sensor (TES) for SAFARI instrument on SPICA
Author(s): P. Khosropanah; B. Dirks; M. Parra-Borderías; M. Ridder; R. Hijmering; J. van der Kuur; L. Gottardi; M. Bruijn; M. Popescu; J. R. Gao; H. Hoevers
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Paper Abstract

Transition edge sensor (TES) is the selected detector for the SAFARI FIR imaging spectrometer (focal plane arrays covering a wavelength range from 30 to 210 μm) on the Japanese SPICA telescope. Since the telescope is cooled to <7 K, the instrument sensitivity is limited by the detector noise. Therefore among all the requirements, a crucial one is the sensitivity, which should reach an NEP (Noise Equivalent Power) as low as 3E-19 W/Hz^0.5 for a base temperature of >50 mK. Also the time constant should be below 8 ms. We fabricated and characterized low thermal conductance transition edge sensors (TES) for SAFARI instrument on SPICA. The device is based on a superconducting Ti/Au bilayer deposited on suspended SiN membrane. The critical temperature of the device is 155 mK. The low thermal conductance is realized by using narrow SiN ring-like supporting structures. All measurements were performed having the device in a light-tight box, which to a great extent eliminates the loading of the background radiation. We measured the current-voltage (IV) characteristics of the device in different bath temperatures and determine the thermal conductance (G) to be equal to 1.66 pW/K. This value corresponds to a noise equivalent power (NEP) of 1E-18 W/√Hz. The current noise and complex impedance is also measured at different bias points at 25 mK bath temperature. The measured electrical (dark) NEP is 2E-18 W/√Hz, which is about a factor of 2 higher than what we expect from the thermal conductance that comes out of the IV curves. Despite using a light-tight box, the photon noise might still be the source of this excess noise. We also measured the complex impedance of the same device at several bias points. Fitting a simple first order thermal-electrical model to the measured data, we find an effective time constant of about 65 μs and a thermal capacity of 3-4 fJ/K in the middle of the transition

Paper Details

Date Published: 15 July 2010
PDF: 9 pages
Proc. SPIE 7741, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V, 77410L (15 July 2010); doi: 10.1117/12.857725
Show Author Affiliations
P. Khosropanah, SRON Netherlands Institute for Space Research (Netherlands)
B. Dirks, SRON Netherlands Institute for Space Research (Netherlands)
M. Parra-Borderías, Univ. de Zaragoza (Spain)
M. Ridder, SRON Netherlands Institute for Space Research (Netherlands)
R. Hijmering, SRON Netherlands Institute for Space Research (Netherlands)
J. van der Kuur, SRON Netherlands Institute for Space Research (Netherlands)
L. Gottardi, SRON Netherlands Institute for Space Research (Netherlands)
M. Bruijn, SRON Netherlands Institute for Space Research (Netherlands)
M. Popescu, SRON Netherlands Institute for Space Research (Netherlands)
J. R. Gao, SRON Netherlands Institute for Space Research (Netherlands)
Delft Univ. of Technology (Netherlands)
H. Hoevers, SRON Netherlands Institute for Space Research (Netherlands)


Published in SPIE Proceedings Vol. 7741:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V
Wayne S. Holland; Jonas Zmuidzinas, Editor(s)

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