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

Noise performance of a balanced waveguide NbN HEB mixer utilizing a GaN buffer-layer at 1.3 THz

Sascha Krause, Denis Meledin, Vincent Desmaris, Alexey Pavolotsky, Victor Y. Belitsky

Published Jan 1, 2018• 1 citation
OpenAlex

Abstract

We report on the initial measurement results of a balanced waveguide phonon cooled NbN mixer employing a 5.5 µm thin GaN membrane, which was operated at frequencies around 1.3 THz. The uncorrected DSB noise temperature amounts to approximately 750 K at 1 GHz IF and increases to only 900 K at 4 GHz IF, which was deduced from the standard Y-factor measurement technique. The recorded IF spectrum from 0.5 GHz to 8 GHz suggests a measured noise bandwidth of approximately 7 GHz owing to the employment of a GaN buffer-layer, which promotes the single crystal growth of NbN films and provides high phonon transparency, thus lowering the phonon escape time. We emphasize with the implementation of a waveguide balanced receiver scheme and using NbN/GaN mixers the possibility to extend the operational IF range of phonon cooled NbN HEBs, yet providing low noise performance.

Related papers

Gain bandwidth of NbN HEB mixers on GaN buffer layer operating at 2 THz local oscillator frequency

Sergey V. Antipov, Andrey Trifonov, Sascha Krause +4 more

In this paper, we present IF bandwidth measurement results of NbN HEB mixers, which are employing NbN thin films grown on a GaN buffer-layer. The HEB mixers were operated in the heterodyne regime at a bath temperature of approximately 4.5 K and with a local oscillator operating at a frequency of 2 THz. A quantum cascade laser served as the local oscillator and a reference synthesizer based on a BWO generator (130-160 GHz) and a semiconductor superlattice (SSL) frequency multiplier was used as a signal source. By changing the LO frequency it was possible to record the IF response or gain bandwidth of the HEB with a spectrum analyzer at the operation point, which yielded lowest noise temperature. The gain bandwidth that was recorded in the heterodyne regime at 2 THz amounts to approximately 5 GHz and coincides well with a measurement that has been performed at elevated bath temperatures and lower LO frequency of 140 GHz. These findings strongly support that by using a GaN buffer-layer the phonon escape time of NbN HEBs can be significantly lower as compared to e.g. Si substrate, thus, providing higher gain bandwidth.

•Jan 1, 2017•0 citations

Design of a wideband balanced waveguide HEB mixer employing a GaN buffer-layer for the 1-1.5 THz band

Sascha Krause, Denis Meledin, Vincent Desmaris +1 more

We present the design and implementation of a wideband balanced waveguide NbN HEB mixer employing a GaN substrate in the frequency range of 1 - 1.5 THz.The balanced receiver scheme consisting of a 90˚ RF hybrid, a pair of NbN phonon-cooled HEB mixers and a 180˚ IF hybrid has major advantages over the single-ended configuration. The 3 dB RF hybrid is employed to couple the RF and LO signal into the HEBs, and allows for the efficient use of available LO power. Furthermore, the usually small IF bandwidth of phonon-cooled NbN HEB mixers has been addressed by employing a GaN substrate instead of a conventional substrate, e.g., Si or quartz. It has recently been shown that using GaN substrate reduces the escape time of phonons from NbN bridge to the substrate and thus, prospectively enhances the overall cooling rate of hot electrons and yielding higher IF bandwidth. The mixer housing is implemented in a back-end configuration and has been fabricated by means of a micro-machining method, providing excellent control of the dimensions and smoothness of the all-metal waveguide components. The expected RF performance of the proposed HEB design as well as its fabrication and DC characterization are presented

•Jan 1, 2017•1 citation

NbN phonon-cooled hot-electron bolometer mixer for terahertz heterodyne receivers

Gregory N Gol'tsman, Yu. B. Vachtomin, Sergey V. Antipov +8 more

We present the results of our studies of NbN phonon-cooled HEB mixers at terahertz frequencies. The mixers were fabricated from NbN film deposited on a high-resistivity Si substrate with an MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 x 0.2 μm2 active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. The largest gain bandwidth of 5.2 GHz was achieved for a mixer based on 2 nm thick NbN film deposited on MgO layer over Si substrate. The gain bandwidth of the mixer based on 3.5 nm NbN film deposited on Si with MgO is 4.2 GHz and the noise bandwidth for the same device amounts to 5 GHz. We also present the results of our research into decrease of the direct detection contribution to the measured Y-factor and a possible error of noise temperature calculation. The use of a square nickel cell mesh as an IR-filter enabled us to avoid the effect of direct detection and measure apparent value of the noise temperature which was 16% less than that obtained using conventional black polyethylene IR-filter.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Mar 25, 2005•11 citations

Noise Temperature Measurements of NbN phonon-cooled Hot Electron Bolometer Mixer at 2.5 and 3.8 THz

Yu. B. Vachtomin, Sergey V. Antipov, S. N. Maslennikov +6 more

We present the results of noise temperature measurements of NbN phonon-cooled HEB mixers based on a 3.5 nm NbN film deposited on a high-resistivity Si substrate with a 200 nm thick MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 gm x 0.2 p,m active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. We also present the results of direct detection contribution to the measured Y-factor and of a possible error of noise temperature calculation. This error was more than 8% for the mixer with in-plane dimensions of 2.4 x 0.16 [trn 2 at the optimal noise temperature point. The use of a mesh filter enabled us to avoid the effect of direct detection and decrease optical losses by 0.5 dB. The paper is concluded by the investigation results of the mixer polarization response. It was shown that the polarization can differ from the circular one at 3.8 THz by more than 2 dB.

•Jan 1, 2004•6 citations

Phonon-cooled NbN HEB Mixers for Submillimeter Wavelengths

Jonathan H. Kawamura, R. Blundell, Edward Tong +4 more

The noise performance of receivers incorporating NbN phonon-cooled superconducting hotelectron bolometric mixers is measured from 200 GHz to 900 GHz. The mixer elements are thin-film (thickness — 4 nm) NbN with —5 to 40 1= 2 area fabricated on crystalline quartz substrates. The receiver noise temperature from 200 GHz to 900 GHz demonstrates no unexpected degradation with increasing frequency, being roughly T Rx 1-2 K GHz -1 . The best receiver noise temperatures are 410 K (DSB) at 430 GHz, 483 K at 636 GHz, and 1150 K at 800 GHz.

Softwaretechnik-Trends•Jan 1, 1997•5 citations

GAIN BANDWIDTH OF PHONON-COOLED HEB MIXER MADE OF NBN THIN FILM WITH MgO BUFFER LAYER ON Si.

Yu. B. Vachtomin, Matvey I. Finkel, Sergey V. Antipov +5 more

We present recently obtained values for gain bandwidth of NbN HEB mixers for different substrates and film thicknesses and for MgO buffer layer on Si at LO frequency of 0.85-1 THz. The maximal bandwidth, 5.2 GHz, was achieved for the device on MgO buffer layer on Si with a 2 nm thick NbN film. Functional devices based on NbN films of such thickness were fabricated for the first time due to an improvement of superconducting properties of NbN film deposited on MgO buffer layer on Si substrate. Introduction. In the last years, the development of HEB mixers has reached such a high level that these devices can be successfully utilized in heterodyne receivers of THz frequency range. Their high sensitivity and low LO power make them suitable for radioastronomic observations on space- and airbom platforms. An NbN HEB mixer seems to be a

•Mar 1, 2002•11 citations
We report on the initial measurement results of a balanced waveguide phonon cooled NbN mixer employing a 5.5 µm thin GaN membrane, which was operated at frequencies around 1.3 THz. The uncorrected DSB noise temperature amounts to approximately 750 K at 1 GHz IF and increases to only 900 K at 4 GHz IF, which was deduced from the standard Y-factor measurement technique. The recorded IF spectrum from 0.5 GHz to 8 GHz suggests a measured noise bandwidth of approximately 7 GHz owing to the employment of a GaN buffer-layer, which promotes the single crystal growth of NbN films and provides high phonon transparency, thus lowering the phonon escape time. We emphasize with the implementation of a waveguide balanced receiver scheme and using NbN/GaN mixers the possibility to extend the operational IF range of phonon cooled NbN HEBs, yet providing low noise performance.
In this paper, we present IF bandwidth measurement results of NbN HEB mixers, which are employing NbN thin films grown on a GaN buffer-layer. The HEB mixers were operated in the heterodyne regime at a bath temperature of approximately 4.5 K and with a local oscillator operating at a frequency of 2 THz. A quantum cascade laser served as the local oscillator and a reference synthesizer based on a BWO generator (130-160 GHz) and a semiconductor superlattice (SSL) frequency multiplier was used as a signal source. By changing the LO frequency it was possible to record the IF response or gain bandwidth of the HEB with a spectrum analyzer at the operation point, which yielded lowest noise temperature. The gain bandwidth that was recorded in the heterodyne regime at 2 THz amounts to approximately 5 GHz and coincides well with a measurement that has been performed at elevated bath temperatures and lower LO frequency of 140 GHz. These findings strongly support that by using a GaN buffer-layer the phonon escape time of NbN HEBs can be significantly lower as compared to e.g. Si substrate, thus, providing higher gain bandwidth.
We present the design and implementation of a wideband balanced waveguide NbN HEB mixer employing a GaN substrate in the frequency range of 1 - 1.5 THz.The balanced receiver scheme consisting of a 90˚ RF hybrid, a pair of NbN phonon-cooled HEB mixers and a 180˚ IF hybrid has major advantages over the single-ended configuration. The 3 dB RF hybrid is employed to couple the RF and LO signal into the HEBs, and allows for the efficient use of available LO power. Furthermore, the usually small IF bandwidth of phonon-cooled NbN HEB mixers has been addressed by employing a GaN substrate instead of a conventional substrate, e.g., Si or quartz. It has recently been shown that using GaN substrate reduces the escape time of phonons from NbN bridge to the substrate and thus, prospectively enhances the overall cooling rate of hot electrons and yielding higher IF bandwidth. The mixer housing is implemented in a back-end configuration and has been fabricated by means of a micro-machining method, providing excellent control of the dimensions and smoothness of the all-metal waveguide components. The expected RF performance of the proposed HEB design as well as its fabrication and DC characterization are presented
We present the results of our studies of NbN phonon-cooled HEB mixers at terahertz frequencies. The mixers were fabricated from NbN film deposited on a high-resistivity Si substrate with an MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 x 0.2 μm2 active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. The largest gain bandwidth of 5.2 GHz was achieved for a mixer based on 2 nm thick NbN film deposited on MgO layer over Si substrate. The gain bandwidth of the mixer based on 3.5 nm NbN film deposited on Si with MgO is 4.2 GHz and the noise bandwidth for the same device amounts to 5 GHz. We also present the results of our research into decrease of the direct detection contribution to the measured Y-factor and a possible error of noise temperature calculation. The use of a square nickel cell mesh as an IR-filter enabled us to avoid the effect of direct detection and measure apparent value of the noise temperature which was 16% less than that obtained using conventional black polyethylene IR-filter.
We present the results of noise temperature measurements of NbN phonon-cooled HEB mixers based on a 3.5 nm NbN film deposited on a high-resistivity Si substrate with a 200 nm thick MgO buffer layer. The mixer element was integrated with a log-periodic spiral antenna. The noise temperature measurements were performed at 2.5 THz and at 3.8 THz local oscillator frequencies for the 3 gm x 0.2 p,m active area devices. The best uncorrected receiver noise temperatures found for these frequencies are 1300 K and 3100 K, respectively. A water vapour discharge laser was used as the LO source. We also present the results of direct detection contribution to the measured Y-factor and of a possible error of noise temperature calculation. This error was more than 8% for the mixer with in-plane dimensions of 2.4 x 0.16 [trn 2 at the optimal noise temperature point. The use of a mesh filter enabled us to avoid the effect of direct detection and decrease optical losses by 0.5 dB. The paper is concluded by the investigation results of the mixer polarization response. It was shown that the polarization can differ from the circular one at 3.8 THz by more than 2 dB.
The noise performance of receivers incorporating NbN phonon-cooled superconducting hotelectron bolometric mixers is measured from 200 GHz to 900 GHz. The mixer elements are thin-film (thickness — 4 nm) NbN with —5 to 40 1= 2 area fabricated on crystalline quartz substrates. The receiver noise temperature from 200 GHz to 900 GHz demonstrates no unexpected degradation with increasing frequency, being roughly T Rx 1-2 K GHz -1 . The best receiver noise temperatures are 410 K (DSB) at 430 GHz, 483 K at 636 GHz, and 1150 K at 800 GHz.
We present recently obtained values for gain bandwidth of NbN HEB mixers for different substrates and film thicknesses and for MgO buffer layer on Si at LO frequency of 0.85-1 THz. The maximal bandwidth, 5.2 GHz, was achieved for the device on MgO buffer layer on Si with a 2 nm thick NbN film. Functional devices based on NbN films of such thickness were fabricated for the first time due to an improvement of superconducting properties of NbN film deposited on MgO buffer layer on Si substrate. Introduction. In the last years, the development of HEB mixers has reached such a high level that these devices can be successfully utilized in heterodyne receivers of THz frequency range. Their high sensitivity and low LO power make them suitable for radioastronomic observations on space- and airbom platforms. An NbN HEB mixer seems to be a