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- Otto, Ernst, 1971
(författare)
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Cold-Electron Bolometers fabricated with Direct Write Technology for Microwave Receiver systems
- 2017
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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.
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| 2. |
- Tan, B. K., et al.
(författare)
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Experimental Investigation of a 220 GHz Planar Multiple Bridges Superconducting Switch
- 2016
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Ingår i: 2015 8th Uk, Europe, China Millimeter Waves and Thz Technology Workshop. - 2378-8275.
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Konferensbidrag (refereegranskat)abstract
- We present preliminary measured responses of a planar superconducting on/off switch centred at the 220 GHz. The superconducting switch, comprising three niobium nitride (NbN) bridges, deposited across the slotline section of a back-to-back unilateral finline, made of a similar superconducting material. The transmission characteristics of the superconducting switch illuminated by a sub-millimetre source were measured using a superconductor-insulator-superconductor (SIS) chip as direct detector. The NbN bridges were switched from the superconducting state to the normal state by a bias current exceeding the critical current of the bridges. With this arrangement, we have measured a switching dynamic range of similar to 13 dB at 245 GHz, demonstrating the successful operation of the multiple NbN bridges planar superconducting on/off switch.
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| 3. |
- Tan, Boon Kok, et al.
(författare)
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Experimental Investigation of a Superconducting Switch at Millimeter Wavelengths
- 2016
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Ingår i: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 6:1, s. 121-126
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Tidskriftsartikel (refereegranskat)abstract
- We present preliminary measured responses of a planar superconducting on/off switch operating at millimeter wavelengths. The superconducting switch, comprising three niobium nitride (NbN) bridges, is deposited across the slotline section of a back-to-back unilateral finline. The transmission characteristics of the superconducting switch illuminated by a millimeter source was measured using a superconductor-insulator-superconductor (SIS) tunnel junction as direct detector. The NbN bridges were switched from the superconducting state to the normal state by passing current through the bridges with magnitude that exceeds its critical current value. With this arrangement, we have measured a typical switching dynamic range of approximately 10 dB across the 205-240 GHz band, with the highest dynamic range of ?20 dB at 230 GHz. This demonstrated the successful operation of the multiple NbN bridges as a planar superconducting on/off switch.
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| 4. |
- Tan, B. K., et al.
(författare)
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Investigation of the dynamic range of superconducting nano-bridge switches
- 2015
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Ingår i: 26th International Symposium on Space Terahertz Technology, ISSTT 2015; Cambridge; United States; 16 March 2015 through 18 March 2015.
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Konferensbidrag (refereegranskat)abstract
- We present the design of planar superconducting on/off switch comprising a number of high normal resistance nano-bridges deposited across a the slot of a unilateral finline. We have simulated the performance of this device and have shown that it has a much larger dynamic range than a single nano-bridge fabricated from the same material (Niobium Nitride, NbN). The response of a single bridge device was measured either directly using a terahertz power meter or by using superconductor-insulator-superconductor (SIS) device as direct detector. In either method, we have demonstrated good agreement between simulations and measurements, and therefore confirmed the integrity of our analysis of the device performance. We have recently designed and fabricated multiple nano-bridges superconducting switches using 50m thick NbN film. The measurement of these devices is currently in progress and we expect to report the results in the forthcoming ISSTT conference in March.
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