Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

IEEE Transactions on Applied Superconductivity

Noise Measurements in Hot-Electron Titanium Nanobolometers

Boris S. Karasik, Sergei V. Pereverzev, David I. Olaya, Jian Wei, M. E. Gershenson, Andrei V. Sergeev

Published Jun 1, 2009• 13 citations
Publisher

Abstract

We are presenting experimental results on the electrical noise in small titanium hot-electron nanobolometers with the critical temperature above 300 mK. The noise data demonstrate good agreement with the conventional bolometer theory prediction. The noise is dominated by the thermal energy fluctuations (phonon noise) when the operating temperature is set just a few mK below the superconducting transition. The corresponding noise equivalent power (NEP) is about 3 times 10-18W/Hz1/2for the smallest measured device. The relative NEP's for the two devices measured scale roughly as the square root of the device volume as one would expect from the theory. Therefore an additional factor of 2-3 reduction of NEP may be feasible if the length and width of our device are further reduced. The demonstrated combination of the low NEP and the relatively high operating temperature is attractive for submillimeter low-background applications.

DOI
10.1109/tasc.2009.2019426

Related papers

Record-Low NEP in Hot-Electron Titanium Nanobolometers

Boris S. Karasik, David I. Olaya, Jian Wei +5 more

We are developing hot-electron superconducting transition-edge sensors (TES) capable of counting THz photons and operating at . We fabricated superconducting Ti nanosensors with Nb contacts with a volume of on planar Si substrates and have measured the thermal conductance in the material, G=4times10-3W/K at 0.3 K, caused predominantly by the weak electron-phonon coupling. The corresponding phonon-noise NEP=3times10-19W/Hz1/2. Detection of single optical photons (1550 nm and 670 nm wavelength) has been demonstrated for larger devices and yielded the thermal time constants of 30 mus at 145 mK and of 25 mus at 190 mK. This hot-electron direct detector (HEDD) is expected to have a small enough energy fluctuation noise for detecting individual photons with v>THz where NEP~3times10-20W/Hz1/2is needed for spectroscopy in space.

IEEE Transactions on Applied Superconductivity•Jun 1, 2007•40 citations

Demonstration of high optical sensitivity in far-infrared hot-electron bolometer

Boris S. Karasik, R. Cantor

We report on the measurement of a very low noise equivalent power of 3×10−19 W/Hz1/2 at 620 GHz in a superconducting antenna-coupled hot-electron bolometer. The sensing element is a micron-size titanium transition-edge sensor with NbTiN superconducting contacts fabricated on a sapphire substrate. The high sensitivity is due to the small device volume, low operating temperature, and weak electron-phonon coupling in titanium film. Measurements were done using a cryogenic black body emitter producing well-controlled femtowatt power levels. The achieved optical sensitivity is suitable for the low-background spectroscopy of molecular lines on next generation space telescopes.

Applied Physics Letters•May 9, 2011•59 citations

Electron temperature fluctuation noise in hot-electron superconducting mixers

Hans Erik Ekström, Boris S. Karasik

An experimental study is presented of the output noise in hot-electron superconducting NbN bolometer mixers. Fluctuations of the electron temperature have been shown to be the main source of electrical noise. The rolloff frequency of the spectral noise density corresponds well to the inverse electron temperature relaxation time (≊230 ps). Equivalent noise data have been obtained for the device at a physical temperature within superconducting transition region, and at a somewhat lower physical temperature with the device pumped by 350 GHz radiation to reach the same operating point. The single sideband (SSB) mixer noise temperature due to intrinsic noise mechanisms for the NbN device is estimated to 360 K independent of radiation frequency. A larger critical current density may promote a further reduction of the intrinsic conversion loss of the mixer device.

Applied Physics Letters•Jun 5, 1995•31 citations

Terahertz Direct Detection Behavior of a Superconducting NbN bolometer by Noise Thermometry

Hao Gao, Wei Miao, Kangmin Zhou +1 more

In this paper, we report the investigation of direct detection behavior of a superconducting niobium nitride (NbN) hot electron bolometer (HEB) based on noise thermometry. The HEB consists of a microbridge made from 5.5 nm thick NbN film and a twin slot antenna for radiation coupling. In the microbridge, hot electron system is generated after radiation pumping and it creates extra noise at RF frequencies. We measured the response of the noise at 0.5-1.8 GHz and the noise equivalent power (NEP) of the superconducting NbN HEB at different bias voltages. The measurement result shows that the superconducting NbN HEB has a noise equivalent power of 1.24×10-12W/Hz1/2at its optimal bias point. We also compared the noise equivalent power measured by noise thermometry at two different readout bandwidths. The measured results are found to be in good agreement with the theoretical one.

International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)•Sep 1, 2019•0 citations

Mixing and noise in diffusion and phonon cooled superconducting hot-electron bolometers

Peter John Burke, R. J. Schoelkopf, D. E. Prober +6 more

We report a systematic, comprehensive set of measurements on the dynamics and noise processes in diffusion and phonon-cooled superconducting hot-electron bolometer mixers which will serve as ultralow noise detectors in THz heterodyne receivers. The conversion efficiency and output noise of devices of varying lengths were measured with radio frequency between 8 and 40 GHz. The devices studied consist of 100-Å-thin film Nb bridges connected to thick (1000 Å), high conductivity normal metal (Au) leads. The lengths of the devices studied range from 0.08 to 3 μm. For devices longer than the electron–phonon interaction length Le–ph≡Dτe–ph, with D the diffusion constant and τe–ph−1 the electron–phonon interaction rate, the hot electrons are cooled dominantly by the electron–phonon interaction, which in Nb is too slow for practical applications. If the device length is less than πLe–ph(≈1 μm at 4.2 K), then out diffusion of heat into the high conductivity leads dominates the cooling process. In this limit, the intermediate frequency (IF) bandwidth is found to vary as L−2, with L the bridge length, as expected for diffusion cooling. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low-Tc superconducting bolometric mixer. The dominant component of the output noise decreases with frequency in the same manner as the conversion efficiency, consistent with a model based on thermal fluctuations. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, ranging from 100 to 530 K (double sideband). The crossover from phonon dominated to diffusion dominated behavior is also demonstrated using noise thermometry measurements in the normal state. Scalar measurements of the device differential impedance in the intermediate state agree with a theoretical model which takes into account the thermal and electrical dynamics. We also present detailed comparisons with theoretical predictions of the output noise and conversion efficiency.

Journal of Applied Physics•Feb 1, 1999•43 citations

Investigation of superconducting NbN hot-electron bolometers for terahertz direct detection

Jiaqiang Zhong, Wei Miao, Wen Zhang +2 more

In this paper, we report on the terahertz (THz) direct detection performance of two superconducting niobium nitride (NbN) hot-electron bolometers (HEBs) of different micro-bridge sizes. At the optimum bias point, the two HEB devices show similar thermal conductance (~80nW/K). The measured responsivity coincides well with the electrical responsivity calculated from the measured current-voltage (IV) curves at different bath temperatures. The noise equivalent power (NEP) of the two HEB devices is found to be about 10-12W/√Hz.

URSI General Assembly and Scientific Symposium•Aug 1, 2014•0 citations
We are presenting experimental results on the electrical noise in small titanium hot-electron nanobolometers with the critical temperature above 300 mK. The noise data demonstrate good agreement with the conventional bolometer theory prediction. The noise is dominated by the thermal energy fluctuations (phonon noise) when the operating temperature is set just a few mK below the superconducting transition. The corresponding noise equivalent power (NEP) is about 3 times 10-18W/Hz1/2for the smallest measured device. The relative NEP's for the two devices measured scale roughly as the square root of the device volume as one would expect from the theory. Therefore an additional factor of 2-3 reduction of NEP may be feasible if the length and width of our device are further reduced. The demonstrated combination of the low NEP and the relatively high operating temperature is attractive for submillimeter low-background applications.
We are developing hot-electron superconducting transition-edge sensors (TES) capable of counting THz photons and operating at . We fabricated superconducting Ti nanosensors with Nb contacts with a volume of on planar Si substrates and have measured the thermal conductance in the material, G=4times10-3W/K at 0.3 K, caused predominantly by the weak electron-phonon coupling. The corresponding phonon-noise NEP=3times10-19W/Hz1/2. Detection of single optical photons (1550 nm and 670 nm wavelength) has been demonstrated for larger devices and yielded the thermal time constants of 30 mus at 145 mK and of 25 mus at 190 mK. This hot-electron direct detector (HEDD) is expected to have a small enough energy fluctuation noise for detecting individual photons with v>THz where NEP~3times10-20W/Hz1/2is needed for spectroscopy in space.
We report on the measurement of a very low noise equivalent power of 3×10−19 W/Hz1/2 at 620 GHz in a superconducting antenna-coupled hot-electron bolometer. The sensing element is a micron-size titanium transition-edge sensor with NbTiN superconducting contacts fabricated on a sapphire substrate. The high sensitivity is due to the small device volume, low operating temperature, and weak electron-phonon coupling in titanium film. Measurements were done using a cryogenic black body emitter producing well-controlled femtowatt power levels. The achieved optical sensitivity is suitable for the low-background spectroscopy of molecular lines on next generation space telescopes.
An experimental study is presented of the output noise in hot-electron superconducting NbN bolometer mixers. Fluctuations of the electron temperature have been shown to be the main source of electrical noise. The rolloff frequency of the spectral noise density corresponds well to the inverse electron temperature relaxation time (≊230 ps). Equivalent noise data have been obtained for the device at a physical temperature within superconducting transition region, and at a somewhat lower physical temperature with the device pumped by 350 GHz radiation to reach the same operating point. The single sideband (SSB) mixer noise temperature due to intrinsic noise mechanisms for the NbN device is estimated to 360 K independent of radiation frequency. A larger critical current density may promote a further reduction of the intrinsic conversion loss of the mixer device.
In this paper, we report the investigation of direct detection behavior of a superconducting niobium nitride (NbN) hot electron bolometer (HEB) based on noise thermometry. The HEB consists of a microbridge made from 5.5 nm thick NbN film and a twin slot antenna for radiation coupling. In the microbridge, hot electron system is generated after radiation pumping and it creates extra noise at RF frequencies. We measured the response of the noise at 0.5-1.8 GHz and the noise equivalent power (NEP) of the superconducting NbN HEB at different bias voltages. The measurement result shows that the superconducting NbN HEB has a noise equivalent power of 1.24×10-12W/Hz1/2at its optimal bias point. We also compared the noise equivalent power measured by noise thermometry at two different readout bandwidths. The measured results are found to be in good agreement with the theoretical one.
We report a systematic, comprehensive set of measurements on the dynamics and noise processes in diffusion and phonon-cooled superconducting hot-electron bolometer mixers which will serve as ultralow noise detectors in THz heterodyne receivers. The conversion efficiency and output noise of devices of varying lengths were measured with radio frequency between 8 and 40 GHz. The devices studied consist of 100-Å-thin film Nb bridges connected to thick (1000 Å), high conductivity normal metal (Au) leads. The lengths of the devices studied range from 0.08 to 3 μm. For devices longer than the electron–phonon interaction length Le–ph≡Dτe–ph, with D the diffusion constant and τe–ph−1 the electron–phonon interaction rate, the hot electrons are cooled dominantly by the electron–phonon interaction, which in Nb is too slow for practical applications. If the device length is less than πLe–ph(≈1 μm at 4.2 K), then out diffusion of heat into the high conductivity leads dominates the cooling process. In this limit, the intermediate frequency (IF) bandwidth is found to vary as L−2, with L the bridge length, as expected for diffusion cooling. The shortest device has an IF bandwidth greater than 6 GHz, the largest reported for a low-Tc superconducting bolometric mixer. The dominant component of the output noise decreases with frequency in the same manner as the conversion efficiency, consistent with a model based on thermal fluctuations. The noise bandwidth is larger than the gain bandwidth, and the mixer noise is low, ranging from 100 to 530 K (double sideband). The crossover from phonon dominated to diffusion dominated behavior is also demonstrated using noise thermometry measurements in the normal state. Scalar measurements of the device differential impedance in the intermediate state agree with a theoretical model which takes into account the thermal and electrical dynamics. We also present detailed comparisons with theoretical predictions of the output noise and conversion efficiency.
In this paper, we report on the terahertz (THz) direct detection performance of two superconducting niobium nitride (NbN) hot-electron bolometers (HEBs) of different micro-bridge sizes. At the optimum bias point, the two HEB devices show similar thermal conductance (~80nW/K). The measured responsivity coincides well with the electrical responsivity calculated from the measured current-voltage (IV) curves at different bath temperatures. The noise equivalent power (NEP) of the two HEB devices is found to be about 10-12W/√Hz.