Journal of Experimental and Theoretical Physics Letters

Electron cooling in a normal-metal hot-electron bolometer

Michael A. Tarasov, L. S. Kuzmin, Mikhail Yu. Fominskii, Ian Jasper Agulo, Alexei Kalabukhov

Published Dec 1, 2003• 8 citations

Abstract

Normal-metal hot-electron bolometers, each of which contains two superconductor-insulator-normal metal (SIN) junctions for electron cooling and two SIN junctions for temperature measurements, were fabricated and experimentally studied. The electron cooling by SIN junctions is an analog of the Peltier effect and allows one to reduce the effective electron temperature of a bolometer. The electron temperature was determined from the ratio of the differential resistance to normal one for several values of a constant bias. At a phonon temperature of 250 mK, the resistance ratio at zero bias reached 1000, which was close to the theoretical value for an ideal SIN junction. A decrease in the electron temperature from 250 to 90 mK was obtained.

DOI: 10.1134/1.1648293

Related papers

Ultrasensitive Cold-Electron Bolometer

Ian Jasper Agulo

The Cold-Electron Bolometer (CEB) is an ultrasensitive device designed for the detection of cosmic microwave background radiation. The key to its sensitivity is the electron cooling of the absorber by the superconductor-insulator-normal metal (SIN) tunnel junction. At a voltage near and below the superconducting gap, the electrons in the absorber are cooled well below the phonon temperature of the normal metal. This translates to the enhanced sensitivity of the CEB. This thesis describes the work we have done on the optimization of electron cooling of the normal metal absorber, and our measurement of the sensitivity of the CEB. We have optimized the electron cooling of the absorber by SIN tunnel junctions. The best electron cooling was achieved when normal metal traps were added in proximity to the superconducting electrodes in addition to the advanced geometry of the superconducting electrodes. With these modifications, we have decreased the electron temperature by 198 mK. With just the advanced geometry, the electron temperature drop was 129 mK. With just a simple geometry, the drop in temperature was 56 mK.The noise equivalent power (NEP) of the CEB was also measured at 100 mK to be at the level of 10^-18 W/Hz^1/2 at 1 kHz. The NEP was obtained by measuring the noise of the CEB, and then dividing that by its power responsivity, dV/dP. The main limitation in our measurements was the noise component from the amplifier. Finally, we have made measurements on the temperature sensitivity of the SIN tunnel junctions. We have compared the sensitivity between single and ten SIN junctions in series and found that it increases proportionally to the number of junctions. The best temperature responsivity obtained for 10 junctions was approximately 15 μV/mK. Using such thermometer, we have been able to measure the temperature stability of the Oxford Instruments cryogenfree refrigerator to be plus/minus 250 μK for a period of 8 hours. The resolution of the thermometer was measured to be plus/minus100 μK, limited by the noise due to the amplifier. The current and future works are also discussed. These include: a CEB array designed to distribute the total power load, improving further the sensitivity; a one-thousand SIN tunnel junction series thermometer in order to realize and understand the fundamental limitation of such a device; a superconducting cold-electron bolometer (SCEB) for high background power loads; and different read-out systems including an on-chip quasiparticle amplifier (QPA).

Aug 1, 20070 citations

Optimal Cold-Electron Bolometer with a Superconductor-Insulator-Normal Tunnel Junction and an Andreev Contact

L. S. Kuzmin

A novel concept of the optimal Cold-Electron Bolometer (CEB) with a Superconductor-Insulator-Normal (SIN) Tunnel Junction and Andreev SN contact has been proposed. This concept has been developed to improve noise properties of the CEB by increasing current responsivity for SQUID readout (in voltage-biased mode) in comparison with classical CEB concept comprising two SIN tunnel junctions. In this configuration the power of incoming signal is not split between two series junctions and the current response of a single junction is twice larger in comparison with double junction structure. The signal is concentrated from antenna to an absorber through capacitance of the tunnel junction from one side and Andreev contact from another side. HF matching is realized by resistance of a normal metal absorber that is independent on tunnel junction parameters. The volume of a normal metal is partly squeezed due to proximity effect of a superconducting electrode from the Andreev contact that also increases efficiency of the electron cooling. The concept is based on direct electron cooling of the absorber by SIN tunnel junction that serves as negative electrothermal feedback for the signal. Noise properties are considerably improved by decreasing the electron temperature. Ultimate performance of the CEB is determined by optical load converted to shot noise of the signal readout. The goal is to achieve noise-equivalent power (NEP) of the CEB with standard SQUID readout less than photon noise. Ultimate NEP better than photon noise can be achieved practically in wide range of power loads from 0.1 fW (SPICA) to 30 pW (OLIMPO, CLOVER, PILOT). Applicability of the CEB to post-Herschel space missions looks very promising.

May 1, 20064 citations

The Resistive Transition of an Aluminium Hot Electron Bolometer Mixer with Normal Metal Cooling Banks

A. H. Verbruggen, T. M. Klapwijk, Wolfgang Belzig +1 more

We perform a theoretical analysis based on the superconducting proximity-effect model for the resistive transition of an aluminium superconducting hot electron bolometer mixer when the cooling banks are in the normal state. We compare our calculated result with a recently reported measurement. Our calculation qualitatively reproduces the observed feature in which the resistance drops quickly around Tc with decreasing temperature, but saturates at a value roughly being one half of the normal state resistance. It also opens the question about which type of cooling banks (normal or superconductor) is favourably for low noise performance.

Softwaretechnik-TrendsDec 1, 20013 citations

Terahertz spectroscopy with a Josephson oscillator and a SINIS bolometer

Michael A. Tarasov, L. S. Kuzmin, Е. А. Степанцов +5 more

The voltage response of a thin-film normal-metal hot-electron bolometer based on a SINIS (superconductor-insulator-normal metal-insulator-superconductor) structure to the radiation of a high-temperature Josephson junction in the terahertz frequency region was measured. Bolometers were integrated with planar log-periodic and double-dipole antennas, and Josephson junctions were integrated with log-periodic antennas. Measurements showed that the Josephson junction at a temperature of 260 mK was overheated by the transport current, so that its electron temperature exceeded 3 K at a bias voltage of 1 mV. The maximum response of a bolometer with a double-dipole antenna was observed at a frequency of 300 GHz, which agreed well with the calculated value. The Josephson radiation was observed at frequencies up to 1.7 THz. The voltage response of a bolometer reached 4×10 8 V/W, and the total noise-equivalent power reached 1.5×10 −17 W/Hz 1/2 .

Journal of Experimental and Theoretical Physics LettersMar 1, 200410 citations

SINIS bolometer with a suspended absorber

Michael A. Tarasov, Valeryan S. Edel'man, Sumedh Mahashabde +6 more

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.

Journal of Physics Conference SeriesMar 1, 20182 citations

Study of the superconductor-normal metal interface in hot-electron bolometer mixers

Ю.Д. Третьяков, Matvey I. Finkel, P. Larionov +5 more

During the last few years significant progress has been made in the field of hot-electron bolometer (HEB) mixers. It has been possible to combine a low noise temperature and high stability of phonon-cooled HEBs with an ultrawide gain bandwidth of the diffusion-cooled HEBs in a single device and thus create HEB mixers which offer a noise temperature of 5hν/kB across a 7-GHz band. The essential ingredient of this success is the in situ fabrication technology, where the deposition of the gold contacts follows the deposition of the superconducting film without vacuum breaking. Despite the evident technological breakthrough, the details of certain physical processes occurring both at the superconductor-normal metal (SN) interface and in the superconducting bridge are not completely understood in terms of their influence on the mixer performance. In particular, it is still unclear to what extent the properties of the SN interface are affected by the deposition temperatures of the superconductor and the normal metal, and also by the time interval elapsed between the deposition processes. We will gain some insight into the matter by studying the behaviour of the superconducting transition as a function of the deposition temperatures and time delay. A better understanding of this issue will allow us to move forward the HEB mixer technology towards new applications.

Jan 1, 20120 citations