Reduction of Phonon Escape Time for NbN Hot Electron Bolometers by Using GaN Buffer Layers

Krause, Sascha; Mityashkin, Vladislav; Antipov, S. V.; Gol’tsman, G.; Meledin, Denis; Desmaris, Vincent; Belitsky, Victor; Rudziński, M.

doi:10.1109/tthz.2016.2630845

Cited by 9 publications

(11 citation statements)

References 30 publications

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“…For the modeling, the electron DOI: 10.1109/TTHZ.2019.2945203 , This paper has been published in IEEE Trans.THz,Sci.Technol. v.9, (2019) / Open Access 6 temperature Te is assumed to be equal to Tc [14], [21]. The phonon temperature (Tph =0.8 Te) was calculated using the system of two heat balance equations: electron-phonon and phonon-substrate [32].…”

Section: Discussionmentioning

confidence: 99%

“…This approach was frequently utilized for HEB mixer studies, and its validity has been confirmed for NbN HEB mixers (see e.g. [14]). For MgB2 HEBs, the I(V)-curves under the optimal power 700 GHz, 1.6 THz, and 2.6 THz LOs have been confirmed to correspond well to the I(V) without an LO, but at a temperature close to Tc [22].…”

Section: B Noise and Gain Characterizationmentioning

confidence: 95%

“…There have been some efforts to enhance the gain bandwidth of NbN HEBs by initiating a faster phonon escape through an improved film-substrate interface system in various substrate materials [14], [15]. Despite some improvements in the noise temperature, the enhanced IF bandwidth in NbN HEBs has only been reported up to 5-6 GHz.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers

Acharya

Novoselov

Cherednichenko

2019

IEEE Trans. THz Sci. Technol.

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We present an experimental study of gain and noise bandwidths in superconducting MgB2 hot-electron bolometer (HEB) THz mixers in a 0.1-20 GHz intermediate frequency range. At an elevated temperature and with a 90 GHz local oscillator, we measure a gain bandwidth of 13-14 GHz, which is the first accurate data for ultrathin MgB2 films. The output noise spectrum has its maximum in the 100 K-200 K range, depending on the temperature (or the LO power) and the bias point, and its spectrum also confirms the gain bandwidth data obtained with the mixing experiment. Using both the gain and the output noise spectra, we obtain the mixer input noise temperature, which is nearly constant up to 20 GHz. Using the measured data and the HEB mixer theory, we argue that noise bandwidth in the current MgB2 HEB mixers is 30 GHz.

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Section: Discussionmentioning

confidence: 99%

Section: B Noise and Gain Characterizationmentioning

confidence: 95%

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Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers

Acharya

Novoselov

Cherednichenko

2019

IEEE Trans. THz Sci. Technol.

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“…Alternative buffer-layers or substrates that yield single crystal NbN films are MgO [17,18], SiC [19,20] and sapphire [21], however, the use of sapphire in waveguide applications is restricted due to its hardness and MgO as a thin buffer-layer on Si or lapped quartz substrates is hygroscopic and may lead to life-time issues in the active device. Moreover, they do not provide a good acoustic match to NbN thin films [22,23], and results in a reduced phonon transparency, which has a negative impact on the achievable IF bandwidth in phonon-cooled HEB devices.…”

Section: Introductionmentioning

confidence: 99%

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Krause

Desmaris

Pavolotsky

et al. 2018

J. Micromech. Microeng.

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Epitaxial growth of ultra-thin NbN films on AlxGa1-xN buffer-layers S Krause, D Meledin, V Desmaris et al. IntroductionThe exploration of the THz frequency range is constantly gaining speed and numerous applications have emerged within research, security, astronomy, biomedicine and metrology in recent years [1][2][3]. The main reason for this relatively late development can be attributed to several technological challenges that had to be overcome. As the dimensions of microwave components usually scale with the wavelength, their size presents a serious issue when the device operation frequency is approaching the THz range. This manifests itself in certain performance limitations due to parasitic capacitances, thermal issues, the excitation of unwanted electromagnetic (EM) modes or excessive RF losses in conductors as the skin depth may approach the roughness of the metal surface. Waveguides for guiding THz EM waves offer wideband operation and full confinement of the fields, yet they are also miniaturized and demand high surface quality and accuracy on the waveguide dimensions and alignment. Several different micro fabrication techniques [4] were developed for this purpose and are based on copper electroforming over a thick sacrificial photo resist mold [5,6] or deep Si etching processes [7]. In waveguidebased THz components, the actual substrate becomes more of a delicate membrane-like structure, which reduces the electrical loading of the waveguide and excludes substrate modes. However, it is difficult to manipulate and to place such beams suspended inside the waveguide with high alignment precision. Typically beam leads [8] made of thick electro-plated gold are used for the electrical contacting, however, once the device is mounted it can neither be modified nor removed in a non-destructive matter. One possible approach to overcome the aforementioned issues is based on a Π-shaped Si support frame holder [9], which keeps a thin Si membrane hosting the active device suspended. This concept has been successfully AbstractWe demonstrate the suitability of employing suspended GaN beams on a Π-shaped Si frame for waveguide-based cryogenic THz components and systems. This concept addresses major challenges and provides eased device handling, cryogenic operation, micron-alignment possibilities, high integratability and allows the electrical contacting by using bonding wires. In particular, a balanced hot electron bolometer (HEB) mixer was implemented for frequencies at 1.3 THz with state-of-the-art IF performance, which combines micro-machined all-metal waveguide components in conjunction with a suspended GaN beam. In addition, in order to accomplish a proper design of active or passive components, the accurate knowledge of the effective dielectric constant at THz frequencies is crucial when such membranes are employed. Thus, a direct measurement method based on a resonance structure and an S-parameter measurement between 1 THz and 1.5 THz is also presented.Keywords: THz components, GaN on Si, HEB, waveguide (Some f...

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“…For NbN SNSPDs, reducing β by choice of substrate could lead to improved detection efficiency at longer photon wavelengths [7]. Increasing β has already been shown as a promising route for improving the bandwidth of NbN hot electron bolometers [43], and phonon trapping has been shown to improve single-photon energy resolution in kinetic inductance detectors [44]. The same would improve SNSPD count rates [5].…”

mentioning

confidence: 99%

Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation

Dane

Allmaras

Zhu

et al. 2021

Preprint

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Controlling thermal transport is important for a range of devices and technologies, from phase change memories to next-generation electronics. This is especially true in nano-scale devices where thermal transport is altered by the influence of surfaces and changes in dimensionality. In superconducting nanowire single-photon detectors, the thermal boundary conductance (TBC) between the nanowire and the substrate it is fabricated on influences most of the performance metrics that make these detectors attractive for applications. This includes the maximum count rate, latency, jitter, and quantum efficiency. Despite its importance, the study of TBC in superconducting nanowire devices has not been done systematically, primarily due to the lack of a straightforward characterization method. Here, we show that simple electrical measurements can be used to estimate the TBC between nanowires and substrates and that these measurements match acoustic mismatch theory across a variety of substrates. Numerical simulations allow us to refine our understanding, however, open questions remain. This work should enable thermal engineering in superconducting nanowire electronics and cryogenic detectors for improved device performance.

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Reduction of Phonon Escape Time for NbN Hot Electron Bolometers by Using GaN Buffer Layers

Cited by 9 publications

References 30 publications

Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers

Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation

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Reduction of Phonon Escape Time for NbN Hot Electron Bolometers by Using GaN Buffer Layers

Cited by 9 publications

References 30 publications

Analysis of the Broad IF-Band Performance of MgB2 HEB Mixers

Analysis of the Broad IF-Band Performance of MgB2 HEB Mixers

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Self-Heating Hotspots in Superconducting Nanowires Cooled by Phonon Black-Body Radiation

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Product

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Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers

Analysis of the Broad IF-Band Performance of MgB₂ HEB Mixers