| 1. |
- Lemzyakov, S., et al.
(author)
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Experimental study of a SINIS detector response time at 350 GHz signal frequency
- 2018
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In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 969:1
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Conference paper (peer-reviewed)abstract
- Response time constant of a SINIS bolometer integrated in an annular ring antenna was measured at a bath temperature of 100 mK. Samples comprising superconducting aluminium electrodes and normal-metal Al/Fe strip connected to electrodes via tunnel junctions were fabricated on oxidized Si substrate using shadow evaporation. The bolometer was illuminated by a fast black-body radiation source through a band-pass filter centered at 350 GHz with a passband of 7 GHz. Radiation source is a thin NiCr film on sapphire substrate. For rectangular 10÷100 μs current pulse the radiation front edge was rather sharp due to low thermal capacitance of NiCr film and low thermal conductivity of substrate at temperatures in the range 1-4 K. The rise time of the response was ∼1-10 μs. This time presumably is limited by technical reasons: high dynamic resistance of series array of bolometers and capacitance of a long twisted pair wiring from SINIS bolometer to a room-Temperature amplifier.
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| 2. |
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| 3. |
- Tarasov, Mikhail, 1954, et al.
(author)
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Electrical and optical properties of a bolometer with a suspended absorber and tunneling-current thermometers
- 2017
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 110:24
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Journal article (peer-reviewed)abstract
- We have developed a bolometer with a suspended normal-metal absorber connected to superconducting leads via tunneling barriers. Such an absorber has reduced heat losses to the substrate, which greatly increases the responsivity of the bolometer to over 10(9) V/W at 75 mK when measured by dc Joule heating of the absorber. For high-frequency experiments, the bolometers have been integrated in planar twin-slot and log-periodic antennas. At 300GHz and 100 mK, the bolometer demonstrates the voltage and current response of 3 x 10(8) V/W and 1.1 x 10(4) A/W, respectively, corresponding to the quantum efficiency of similar to 15 electrons per photon. An effective thermalization of electrons in the absorber favors the high quantum efficiency. We also report on how the in-plane-and transverse magnetic fields influence the device characteristics.
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| 4. |
- Tarasov, Mikhail, 1954, et al.
(author)
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Quantum Efficiency of Cold Electron Bolometer Optical Response
- 2015
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In: IEEE Transactions on Terahertz Science and Technology. - 2156-342X .- 2156-3446. ; 5:1, s. 44-48
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Journal article (peer-reviewed)abstract
- In this paper we present the measurements of optical response dependence on power load of a Cold Electron Bolometer integrated in a twin slot antenna. These measurements are also compared to the models of the bolometer limit and the photon counter limit. The responsivity of 0.22*10^9 V/W was measured at 0.22 pW radiation power from a black body at 3.5 K. According to our estimations, for optimized device the voltage responsivity at 100 mK electron temperature can approach Sv=10^10 V/W for power load below 0.1 pW and decreases down to 10^7 V/W at 300 mK for 5 pW signal power in a sample with absorber volume of 5*10^-20 m^3. In the case of low bath temperatures and high applied RF power the changes of tunneling current, dynamic resistance and voltage response are explained by non-thermal energy distribution of excited electrons. Distribution of excited electrons in such system at lower temperatures can be of non-Fermi type, hot electrons with energies of the order of 1 K tunnel from normal metal absorber to superconductor instead of relaxing down to thermal energy kTe in absorber before tunneling. This effect can reduce quantum efficiency of the bolometer at 350 GHz from hf/kTph>100 in ideal case down to single electron per absorbed photon (Q.Eff=1) in the high power case. Methods of preserving high quantum efficiency are discussed.
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| 5. |
- Tarasov, Mikhail, 1954, et al.
(author)
-
SINIS bolometer with a suspended absorber
- 2018
-
In: Journal of Physics: Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 969:1
-
Conference paper (peer-reviewed)abstract
- We have developed a Superconductor-Insulator-Normal Metal-Insulator-Superconductor (SINIS) bolometer with a suspended normal metal bridge. The suspended bridge acts as a bolometric absorber with reduced heat losses to the substrate. Such bolometers were characterized at 100-350 mK bath temperatures and electrical responsivity of over 10 9 V/W was measured by dc heating the absorber through additional contacts. Suspended bolometers were also integrated in planar twin-slot and log-periodic antennas for operation in the submillimetre-band of radiation. The measured voltage response to radiation at 300 GHz and at 100 mK bath temperature is 3∗10 8 V/W and a current response is 1.1∗10 4 A/W which corresponds to a quantum efficiency of ∼15 electrons per photon. An important feature of such suspended bolometers is the thermalization of electrons in the absorber heated by optical radiation, which in turn provides better quantum efficiency. This has been confirmed by comparison of bolometric response to dc and rf heating. We investigate the performance of direct SN traps and NIS traps with a tunnel barrier between the superconductor and normal metal trap. Increasing the volume of superconducting electrode helps to reduce overheating of superconductor. Influence of Andreev reflection and Kapitza resistance, as well as electron-phonon heat conductivity and thermal conductivity of N-wiring are estimated for such SINIS devices.
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