1. Electrical properties of background-limited membrane- isolation TESs for far-IR/subMM spectroscopy M. Kenyon, P. K. Day, C. M Bradford, J. J. Bock, & H. G. Leduc Jet Propulsion Laboratory, Pasadena, CA 91030 * Overview of BLISS. * Bolometer requirements. * Latest results. Outline

2. BLISS-SPICA, -SAFIR Mission : BLISS: assumes 25% instrument & 75% aperture efficiency, single polarization, & chopping. SPICA: Cold 3.5 m telescope under study by Japanese (JAXA). SAFIR: 10x better sensitivity than BLISS-SPICA.

3. Detector requirements: Wavelength Coverage: 40-600  m. Sensitivity: NEP = 3x10 -20 W/Hz 1/2. Time constant:  < 1 s. Operating temperature: T c > 60mK. Objective :

4. Echelle Spectrograph: 40-200  m Design requirements for BLISS : Waveguide Spectrometer: 200-600  m … … WaFIRS: C. M. Bradford et al., SPIE 4850, 1137 (2003). Compact & broad-band spectrometer. Format: 32x32, Pitch: 150  m Wire grid Si x N y beam Frame

5. BLISS demands NEP ~10 -20 W Hz -1/2. Noise limited by. Thermal conductance G ~10 -15 W/K. Micrographs of TESs : 1D Array: Straight Beams 2D Array: Meander Beams Support beam: 700  m x 0.5  m x 0.5  m Support beam: 700  m x 0.35  m x 0.25  m

6. Fabrication Details: Fabrication : 2D Array: Meander Beams Lithography: Canon FPA-3000 EX3 (0.25  m) Thermistor: 20 x 100  m 2 Sputter Mo (50nm)/Au (170 nm). Wet etch. Absorber/supports: 200 x 200  m 2 LPCVD Si x N y. Bias lines: Sputtered Nb BCl 3 /Cl 2 dry etch. Release: XeF 2 dry etch.

7. I-V Characteristics : 1D Array: Straight Beams 2D Array: Meander Beams

8. I-V Characteristics : 1D Array: Straight Beams

9. Bias Power versus Substrate Temperature : 1D Array: Straight Beams 2D Array: Meander Beams G = 72 x 10 -15 W/K G = 19 x 10 -15 W/K T c = 137 mK T c = 71 mK NEP = 1.9 x 10 -19 W Hz -1/2 NEP = 6.1 x 10 -20 W Hz -1/2

10. Bias Power versus Substrate Temperature : 2D Array: Meander Beams

11. G~T G~T 2 G~T 3 2 legs x 120 x 900 x 1  m 3 4 legs x 9 x 900 x 1  m 3 4 legs x 3 x 900 x 1  m 3 4 legs x 3 x 8300 x.5  m 3 4 legs x 0.35 x 700 x.5  m 3 Noise thermometry: Power: P=I 2 R H Johnson Noise: S J =4k b TR J RHRH RJRJ Cross over from G~T 3 to T : G=dP/dT - K. Schwab et al., Nature 404, 974 (2000). G~T 1/2

12. Conclusions: Progress to date: Built and tested the thermal conductance G of “compact” membrane design. Confirmed G is reasonable for BLISS. Confirmed  is fast enough for BLISS. Made TES bolometers with T c =70mK.