Leonid Kuzmin and Ian Agulo Through the thorns to the stars! Igenom törnen mot stjärnorna! Через тернии к звездам! Chalmers University of Technology Bolometer Group P5. Cold-Electron Bolometer Array (CEB Array) made by E-Beam Lithography and a Shadow Evaporation Technology Leonid Kuzmin and Ian Agulo FKA190

Leonid Kuzmin, Philip Mauskopf *, and Chalmers University of Technology Bolometer Group Superconducting Cold-Electron Bolometer with JFET readout for OLIMPO balloon telescope Leonid Kuzmin, Philip Mauskopf *, and Dmitry Golubev** *Cardiff University, UK **Karlsruhe Forschungszentrum, Germany EUCAS -2005

OLIMPO Cardiff CLOVER + others Oxford CLOVER Phase Switch Oxford, 3-layer technology JFET Voltage- biased SCEB OLIMPO Cardiff 2-layer Al-Ti Direct Write technology CEB- Series array JFET Current -biased 2-layer Ti-Al Direct Write technology CEB CLOVER + others Oxford SQUID Shadow Evaporation Technology CEB- Parallel array CLOVER Phase Switch Oxford, Cardiff NbN Nanostrip + Finline

Balloon telescope OLIMPO (follower of BOOMERanG) a multi-wavelength survey of galaxy clusters and the cosmic submm/mm background 2.6 meter antenna A few arcmin resolution survey of the sky 150, 220 350, 600 GHz (Background load Po = 3 - 20 pW Background limited bolometers (2*10-17 – 1*10-16 W/Hz1/2), 64 bolom. per channel Bolometers: TES+SQUID readout SiN+JFET readout CEB+JFET (or SQUID) readout Rome Un., Cardiff Un., IROE-CNR (Italy), Caltech (USA), Santa Barbara Un. , DAFNIA/SPP (France), Tel Aviv Un., VTT (finland), Chalmers Univ.

Balloon telescope OLIMPO 1. Channel I: ”2.1 mm” (140 GHz) Power load is relatively high: P0 = 2 – 3 pW Photon noise: Total NEP of CEB should be less than photon noise: NEPtot < NEPphot. Single CEB doesn’t give proper results. Only SCEB could give the proper NEP.

Cold-Electron Bolometer (CEB) with Capacitive Coupling to the Antenna Cold-Electron Bolometer (CEB) with Capacitive Coupling to the Antenna Kuzmin – ISSTT-98

Readout Systems for CEB current measurements SQUID with a bulk input transformer - most sensitive - very complicated Chalmers Un., IREE, IZMIRAN, MSU, VTT (Finland) JFET @ 4K - sensitive current measurements - but high voltage noise - promising with S-I-S’-I-S bolometers Cardiff Un, IREE, Rome Un. HEMT @ 4K with resonance circuits - good for multiplexing - need modulation technique IPHT (Jena), CESR (Toulouse)

CEB with JFET

Cold-Electron Bolometer Noise

JFET amplifier noise We need matching with

Capacitively Coupled Superconducting Cold-Electron Bolometer (SCEB) L. Kuzmin, Microelectronic Engineering, 69 (2003)

SCEB with JFET Total NEP is less than NEPphot for SCEB, total iJFET=10 fA/Hz1/2, R=0.5 kOhm and 0.1 kOhm (one junction), Vol=0.05um3, power load – 2 pW. IV curves are shown for estimation of high dynamic resistance of the junctions.

Series Array of CEBs with JFET readout Circle waveguide is coupled to 4 coplanar lines Each Coplanar line is coupled to 2 CEBs

CEB, Current-biased, Array - 10 junctions Total NEP is less than NEPphot vJFET=2nV/Hz1/2 R=0.5 kOhm (one junction), Vol=0.02um3, power load=2 pW The power is split between bolometers and responsivity is considerably improved.

Total NEP of CEB and NEPphot for series array CEBs in dependence on number of CEBs a) 600 GHz, power load P0 = 20 pW, vJFET=3 nV/Hz1/2 R=0.5 kOhm Vol=0.05um3 Optimal number of CEBs = 20-50. b) 140 GHz, power load P0 = 2 pW, vJFET=2 nV/Hz1/2 R=0.5 kOhm Vol=0.02um3. Optimal number of CEBs = 5-10.

JFET in current-biased mode. Variants: Series array of CEBs Array of SINIS structures without biasing Array of SN – NS Andreev contacts –thermo-voltage without biasing Array of thermocouples (thermo-pile) Combination of thermocouples and superconducting islands (SN Andreev contacts) Array of CEBs – series for DC - parallel for HF

Series Array of CEBs with JFET readout Parallel for HF HF

Conclusions New generation of detectors is needed to measure Cosmic Microwave Background (OLIMPO project) Cold-Electron Bolometer (CEB) with JFET readout – very attractive option! Single CEB with JFET – no chance! Array of CEBs with JFET – the most attractive opportunity SCEB (Superconducting Cold-Electron Bolometer) with JFET – realistic and effective decision