| 1. |
- Dell'Anna, M., et al.
(författare)
-
THz Spectroscopy Using Low Temperature Mesoscopic Devices
- 2012
-
Ingår i: Journal of Low Temperature Physics. - : Springer Science and Business Media LLC. - 0022-2291 .- 1573-7357. ; 167:3-4, s. 467-472
-
Tidskriftsartikel (refereegranskat)abstract
- The prototype of a THz spectroscopic camera based on low temperature mesoscopic devices is presented. The core of this system is an array of Quantum-Dots coupled to Quantum Point Contact sensors. Readout electronics is based on Time Domain Multiplexing combined with Lock-in technique. Results show that such system can reach the sensitivity needed to detect THz emission of materials in a fully passive way.
|
|
| 2. |
- Kuzmin, Leonid, 1946, et al.
(författare)
-
Superconducting subterahertz fast nanoswitch
- 2007
-
Ingår i: JETP Letters. - : Pleiades Publishing Ltd. - 1090-6487 .- 0021-3640. ; 86:4, s. 275-277
-
Tidskriftsartikel (refereegranskat)abstract
- A superconducting thin-film nanoswitch for the subterahertz frequency range has been proposed, developed, fabricated, and tested. The switch makes it possible to modulate the microwave signal or switch it between two branches of a circuit with low losses and high speed. The switch can be naturally integrated with superconducting high-sensitive detectors. Its application makes it possible to avoid the use of massive slow mechanical modulators and to improve the measurement accuracy in decisive astrophysical experiments such as the investigation of the anisotropy of the cosmic microwave background.
|
|
| 3. |
- Mahashabde, Sumedh, 1985, et al.
(författare)
-
Fast Tunable High-Q-Factor Superconducting Microwave Resonators
- 2020
-
Ingår i: Physical Review Applied. - 2331-7019. ; 14:4
-
Tidskriftsartikel (refereegranskat)abstract
- We present fast tunable superconducting microwave resonators fabricated from planar NbN on a sapphire substrate. The 3 lambda/4 wavelength resonators are tuning fork shaped and tuned by passing a dc current that controls the kinetic inductance of the tuning fork prongs. The lambda/4 section from the open end operates as an integrated impedance converter that creates a nearly perfect short for microwave currents at the dc terminal coupling points, thus preventing microwave energy leakage through the dc lines. We measure an internal quality factor Q(int) > 10(5) over the entire tuning range. We demonstrate a tuning range of greater than 3% and tuning response times as short as 20 ns for the maximum achievable detuning. Because of the quasifractal design, the resonators are resilient to magnetic fields of up to 0.5 T.
|
|
| 4. |
- Otto, Ernst, 1971, et al.
(författare)
-
An array of 100 Al-Al2O3-CuSIN tunnel junctions in direct-write trilayer technology
- 2007
-
Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 20:12, s. 1155-1158
-
Tidskriftsartikel (refereegranskat)abstract
- We present superconductor-insulator-normal metal (SIN) tunnel junction thermometers made of arrays of 4-100Al-Al2O3-Cu SIN tunnel junctions fabricated in direct-write technology. The technology is based on in situ evaporation of the superconductive electrode followed by the oxidation and the normal counter-electrode as a first step and deposition of normal metal absorber as a second one. This approach allows one to realize any geometry of the tunnel junctions and of the absorber with no limitation related to the size of the junctions or the absorber, which is not possible using the shadow evaporation technique. Measurements performed at 300 mK showed the high quality of the fabricated tunnel junctions, low leakage currents, and that an R-d/R-n ratio of 500 has been achieved at that temperature. The junctions were characterized as temperature sensors, and voltage versus temperature dependence measurements showed a dV/dT of 0.5 mV K-1 for each single junction, which is typical for this kind of tunnel junction. A temperature resolution of +/- 5 mu K has been achieved which is much better than the previously reported value of +/- 30 mu K for this type of thermometer.
|
|
| 5. |
- Otto, Ernst, 1971, et al.
(författare)
-
Cold-electron bolometer integrated with a unilateral finline
- 2010
-
Ingår i: 21st International Symposium on Space Terahertz Technology 2010, ISSTT 2010; Oxford; United Kingdom; 23 March 2010 through 25 March 2010. - 9781617823626 ; , s. 238-243
-
Konferensbidrag (refereegranskat)abstract
- The Cold-Electron Bolometer (CEB) is a very sensitive millimetre-wave detector which is easy to integrate with planar circuits. CEB detectors have other important features such as high saturation power and very fast response. We have designed, fabricated and tested CEB detectors integrated across the slot of a unilateral finline on silicon substrate. Bolometers were fabricated using e-beam directwrite trilayer technology. The CEB performance was tested in a He3 sorption cryostat HELIOX-AC-V at a bath temperature of 280 mK. To reduce the background power radiation overheating the optical window in the cryostat was equipped with two low-pass filters with cut-off frequency 33 cm-1 and 100 cm-1 and 2 neutral density filters with 10 db attenuation each. DC IV curves were measured in a current bias mode, optical response was measured by irradiating samples with a microwave signal from IMPATT diode at 110 GHz modulated at 127 Hz. These tests were conducted by coupling power directly into the finline chip. The signal response was measured using a lock-in amplifier. The bolometer dark electrical noise equivalent power is estimated to be about NEP=5·10-16 W/Hz1/2.
|
|
| 6. |
- Otto, Ernst, 1971
(författare)
-
Cold-Electron Bolometers fabricated with Direct Write Technology for Microwave Receiver systems
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns the development of microwave detector technology for cosmology instruments and THz imaging, including fabrication of SIN tunnel junctions for thermometry and bolometric detectors, and also phase switch circuits as a part of integrated microwave receiver systems. Cold-Electron Bolometers (CEB) based on Superconductor-Insulator-Normal metal (SIN) tunnel junctions have been developed for employment in sub-millimeter astronomical receivers. While used as direct detectors, their operation principle is based on hot-electron effect in nanoabsorbers and the dependence of SIN junction characteristics on temperature. In this thesis, the technology development for fabricating bolometric detectors based on these principles is presented, as well as CEB devices fabricated with the new technology and operating at 97 - 350 GHz. The successful operation of CEB devices is reported here, including different advanced implementations of bolometers for effective detection of microwave electromagnetic signals. New fabrication technologies developed for manufacturing CEB, on-chip thermometers, THz detectors and Phase Switch devices are presented. The necessity of this development work was determined by the demand of a robust and straightforward process for fabricating CEB devices with SIN tunnel junctions of large area, at high yield and good reproducibility. Advanced procedures developed for fabricating CEB devices include e.g. Direct-Write Trilayer Technology and Ti-based technology that enable fabricating devices of any geometry, with no limitations related to the layout. This is suitable for integrating the devices in planar antennas, such as log-periodic and double-dipole antennas or finline-shaped slotlines. Properly operating CEB devices are demonstrated, characterized by measuring their DC characteristics and RF response at 280-315 mK. RF testing was performed using hot-cold method and using a black-body source heated by external current, with the estimated NEP down to about ~3∙10^-17 W/Hz^1/2 reported. Fabricating and testing these devices allows demonstrating the full functionality of the CEB detector fabricated with new technology and integrated in various planar circuits. All devices presented here were fabricated by the author at Chalmers MC2.
|
|
| 7. |
- Otto, Ernst, 1971
(författare)
-
Direct Write Technology of SIN Tunnel Junctions for Thermometry and Microwave Devices
- 2008
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis concerns development of SIN junction technology for thermometry and microwave detectors, as well as technology of a planar phase switch as a part of integratedmicrowave receiver.Cold-Electron Bolometer (CEB) is a sensitive detector of a microwave radiation, in which SIN tunnel junctions are used for temperature measurement of a nanoscale absorber in thesame way as in SIN thermometers. A novel direct-write trilayer technology and a Ti-based technology were developed for the CEB and thermometry.The trilayer technology is based on in-situ evaporation of the superconductive electrode followed by the oxidation and the normal counter-electrode as a first step and deposition of a normal-metal absorber as a second one. The junctions were characterized as temperature sensors, and a thermometer responsivity of 52 mV/K was observed for an array of 100junctions in series with a temperature resolution of ± 5μK.A novel Ti-based direct-write technology for fabrication of Ti-TiO2-Al tunnel junctions has another advantages related to thickness of the absorber. In particular, a very thin andcompletely flat absorber can be created with no bending parts. The key point of this technology is deposition of Ti film as a base electrode and deposition of Al electrode after oxidation of Ti.The junctions are to be used for fabrication of microwave receivers for sensitive measurements in new generation of telescopes, e.g. CLOVER project including polarizationCosmic Microwave Background (CMB) radiation measurements, BOOMERANG and OLIMPO balloon telescope project which is dedicated to measuring the Sunyaev-Zeldovich effect in clusters of Galaxies.A planar phase switch operating at 97-225 GHz has been developed, fabricated, and tested. The system makes it possible to modulate the microwave signal or switch it between two branches of a circuit with low losses and high speed. The proposed fully planar design allowsthe switch to be integrated into the detector circuit.The phase modulation scheme will be used in high-precision astrophysical experiments such as the investigation of the polarization of the cosmic microwave background.Keywords: SIN tunnel junction, direct write technology, Cold-Electron Bolometer, cryogenicthermometry, phase switch, microwave device, noise equivalent power
|
|
| 8. |
- Otto, Ernst, 1971, et al.
(författare)
-
Direct-write trilayer technology for Al-Al2O3-Cu superconductor-insulator-normal metal tunnel junction fabrication
- 2007
-
Ingår i: Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures. - : American Vacuum Society. - 2166-2754 .- 2166-2746 .- 1071-1023. ; 25:4, s. 1156-1160
-
Tidskriftsartikel (refereegranskat)abstract
- The authors present a novel direct-write trilayer technology for bolometer and thermometry applications. The technology is based on in situ evaporation of the superconductive electrode followed by the oxidation and the normal counterelectrode as a first step and deposition of normal-metal absorber as a second one. This approach allows one to realize any geometry of the tunnel junctions and of the absorber with no limitation related to. the size of the junctions or the absorber, which is not possible using shadow evaporation technique. The proposed new approach is perfectly suited for fabrication of microwave receivers for high-precision measurements in new generation of telescopes such as CLOVER ground-based telescope and OLIMPO balloon telescope projects. Measurements performed at 300 mK showed high quality of fabricated tunnel junctions, low leakage currents, and Rd/Rn ratio of 500 has been achieved at that temperature. The junctions were characterized as temperature sensors, and voltage versus temperature dependence measurements have shown a dV/dT of 0.5 mV/K for each single junction, which is typical for this kind of tunnel junctions. (c) 2007 American Vacuum Society.
|
|
| 9. |
- Otto, Ernst, 1971, et al.
(författare)
-
Finline-integrated cold electron bolometer
- 2010
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819482310 ; 7741
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Cold-Electron Bolometer (CEB) is a sensitive millimetre-wave detector which is easy to integrate with superconducting planar circuits. CEB detectors have other important features such as high saturation power and very fast response. We have fabricated and tested CEB detectors integrated across the slot of a unilateral finline on a silicon substrate. Bolometers were fabricated using two fabrication methods: e-beam direct-write trilayer technology and an advanced shadow mask evaporation technique. The CEB performance was tested in a He3 sorption cryostat at a bath temperature of 280mK. DC I-V curves and temperature responses were measured in a current bias mode, and preliminary measurements of the optical response were made using an IMPATT diode operating at 110GHz. These tests were conducted by coupling power directly into the finline chip, without the use of waveguide or feedhorns. For the devices fabricated in standard direct-write technology, the bolometer dark electrical noise equivalent power is estimated to be about 5×10-16W/ √Hz, while the dark NEP value for the shadow mask evaporation technique devices is estimated to be as low as 3×10-17W/√Hz.
|
|
| 10. |
- Otto, Ernst, 1971, et al.
(författare)
-
Optical response of a titanium-based cold-electron bolometer
- 2013
-
Ingår i: Superconductor Science and Technology. - : IOP Publishing. - 0953-2048 .- 1361-6668. ; 26:8
-
Tidskriftsartikel (refereegranskat)abstract
- We present experimental results on the testing of cold-electron bolometer (CEB) detectors comprised of a thin Ti film absorber and two SIN junctions integrated with a planar antenna. The CEB performance was tested in a He-3 sorption cryostat HELIOX-AC-V at bath temperatures of 280-305 mK. The optical response was measured using the hot/cold load method by flipping a Cu reflector opposite a blackbody surface inside a 3 K shield and using a thermal source with variable temperature. In the first experiment, the detector chip was mounted in an optical sample-holder whose aperture was switched towards or away from a blackbody source changing the incident radiation temperature from 3 K to 270 mK. As a result, we measured the optical response to a 3 K/270 mK radiation temperature change. The measured voltage response value for the detector integrated in a double-dipole antenna was Delta V-out = 120 mu V. This corresponds to a noise equivalent power of NEP = V-n/(dV/dP) = 3.5 x 10(-17) W Hz(-1/2), where dV/dP is the voltage to power response obtained from the incoming power estimation based on the Planck formula.
|
|
