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

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, Victor Y. Belitsky

Published Jan 1, 2017• 1 citation
OpenAlex

Abstract

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

Related papers

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

Sascha Krause, Denis Meledin, Vincent Desmaris +2 more

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.

•Jan 1, 2018•1 citation

A 1.3-THz Balanced Waveguide HEB Mixer for the APEX Telescope

Denis Meledin, Alexey Pavolotsky, Vincent Desmaris +13 more

In this paper, we report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90$\,\times\,$180$\mu{\hbox{m}}$). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light” at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s.

IEEE Transactions on Microwave Theory and Techniques•Dec 18, 2008•101 citations

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

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

Performance of NbN phonon-cooled hot-electron bolometric mixer at Terahertz frequencies

Pavel A. Yagoubov, M. Kroug, H. Merkel +6 more

The performance of a NbN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixer is investigated in the 0.65-3.12 THz frequency range. The device is made from a 3 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are 0.2/spl times/2 /spl mu/m. The results of the DSB noire temperature are: 1300 K at 650 GHz, 4700 K at 2.5 TBz and 10000 K at 3.12 THz. The RF bandwidth of the receiver is at least 2.5 THz. The amount of LO power absorbed in the bolometer is about 100 nW. The mixer is linear to within 1 dB compression up to the signal level 10 dB below that of the LO. The intrinsic single sideband conversion gain is measured to be -9 dB, the total conversion gain -14 dB.

IEEE International Conference on Terahertz Electronics (THz)•Nov 27, 2002•1 citation

Improved bandwidth of a 2 THz hot-electron bolometer heterodyne mixer fabricated on sapphire with a GaN buffer layer

Sergey V. Antipov, Andrey Trifonov, Sascha Krause +6 more

Abstract We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer.

Superconductor Science and Technology•Mar 26, 2019•3 citations
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 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 report about the development, fabrication, and characterization of a balanced waveguide hot electron bolometer (HEB) receiver for the Atacama Pathfinder EXperiment telescope covering the frequency band of 1.25–1.39 THz. The receiver uses a quadrature balanced scheme and two HEB mixers, fabricated from 4- to 5-nm-thick NbN film deposited on crystalline quartz substrate with an MgO buffer layer in between. We employed a novel micromachining method to produce all-metal waveguide parts at submicrometer accuracy (the main-mode waveguide dimensions are 90$\,\times\,180180180\mu{\hbox{m}}$). We present details on the mixer design and measurement results, including receiver noise performance, stability and “first-light” at the telescope site. The receiver yields a double-sideband noise temperature averaged over the RF band below 1200 K, and outstanding stability with a spectroscopic Allan time more than 200 s.
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 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
The performance of a NbN based phonon-cooled Hot Electron Bolometric (HEB) quasioptical mixer is investigated in the 0.65-3.12 THz frequency range. The device is made from a 3 nm thick NbN film on high resistivity Si and integrated with a planar spiral antenna on the same substrate. The in-plane dimensions of the bolometer strip are 0.2/spl times/2 /spl mu/m. The results of the DSB noire temperature are: 1300 K at 650 GHz, 4700 K at 2.5 TBz and 10000 K at 3.12 THz. The RF bandwidth of the receiver is at least 2.5 THz. The amount of LO power absorbed in the bolometer is about 100 nW. The mixer is linear to within 1 dB compression up to the signal level 10 dB below that of the LO. The intrinsic single sideband conversion gain is measured to be -9 dB, the total conversion gain -14 dB.
Abstract We report on the signal-to-noise and gain bandwidth of a niobium nitride (NbN) hot-electron bolometer (HEB) mixer at 2 THz fabricated on a sapphire substrate with a GaN buffer layer. Two mixers with different DC properties and geometrical dimensions were studied and they demonstrated very close bandwidth performance. The signal-to-noise bandwidth is increased to 8 GHz in comparison to the previous results, obtained without a buffer-layer. The data were taken in a quasi-optical system with the use of the signal-to-noise method, which is close to the signal levels used in actual astrophysical observations. We find an increase of the gain bandwidth to 5 GHz. The results indicate that prior results obtained on a substrate of crystalline GaN can also be obtained on a conventional sapphire substrate with a few micron MOCVD-deposited GaN buffer-layer.