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

COMPARISON BETWEEN ELECTRONIC HOT SPOT MODEL AND CURRENT-VOLTAGE CHARACTERISTICS OF SUPERCONDUCTING HOT-ELECTRON BOLOMETERS

D. Wilms Floet

Published Jan 1, 1999• 0 citations
OpenAlex

Abstract

We compare theoretical predictions based on the electronic hot spot (EHS) model for hot electron bolometers with experimental results obtained with a Nb diffusion-cooled bolometer. We calculate the current-voltage, I(V), characteristics both analytically and numerically and find a good agreement with unpumped and pumped experimental I(V) curves. Observed deviations can partially be explained by the thermal conductance of the superconducting parts of the microbridge, which is lower than the normal state value assumed in the analytical model. Remaining deviations are attributed to heat-trapping due to Andreev reflection, resulting in a thermal boundary resistance at the interface. Furthermore, the influence of a finite electron-electron interaction time, which prevents complete thermalization of the electrons, is discussed.

Related papers

A two-dimensional hot-spot mixer model for phonon-cooled hot electron bolometers

H.F. Merkel, P. Khosropanah, Serguei Cherednichenko +3 more

A hot spot model for superconducting hot electron bolometers is presented based on a two-dimensional heat transport equation for electrons and phonons including heat trapping due to quasiparticle bandgap gradients. Skin effect concentrates the RF heating in lateral regions of the bridge and the bias current in the center. A reduction in conversion gain compared to a one-dimensional hot spot model is explained by the RF and bias heating profiles not being identical. An experimentally verified increase of the IF bandwidth from 3.5 GHz to 8 GHz when increasing bias voltage is predicted. IV curves, gain and noise are in very good agreement with measurements.

IEEE Transactions on Applied Superconductivity•Mar 1, 2001•6 citations

A Hot Spot Mixer Model for Superconducting Phonon-Cooled HEB Far Above the Quasiparticle Bandgap

Harald Merkel, P. Khosropanah, Pavel A. Yagoubov +1 more

Abstract — A hot spot mixer model for phonon cooled hot electron bolometers is set up to accurately determine the dependence of the bolometer resistance on bias and absorbed LO power. An one-dimensional power balance for the nonequilibrium electrons containing an electron heat conduction term along the film and a loss term due to phonon escape to the substrate is solved. In the device's operating region of interest the absorbed heating power is usually large enough to heat a part of the bolometer bridge above the critical temperature forming a normal conducting hot spot. In this model heating due to the LO is assumed to be uniform whereas bias heating takes place in the hot spot region only. Solving the nonlinear power balance for the hot spot length allows to predict current-voltage characteristics, required heating powers and regions of optimal operation. Applying a small signal model in a given operating point yields an estimate for the intrinsic conversion gain. I. LARGE SIGNAL MODEL Existing device models for hot electron bolometers [1,2] treat the bolometer as a lumped element. It is assigned an effective temperature for the phonons and another for the electrons at a given bath temperature. In terms of heating bias power and RF power are equivalent and exchangeable. From this a method [3,4] to calculate the absorbed RF power is derived. This method is referred to as "isotherm " method: Operating points with identical device resistance must have identical temperatures since R(To„,,(,,, ) is a single valued monotonous function. Identical temperature implies identical power losses and identical 592

Softwaretechnik-Trends•Mar 1, 1999•5 citations

Rigorous Analysis of a Superconducting Hot-Electron Bolometer Mixer: Theory and Comparison with Experiment

Rainer S. Nebosis, Alexei D. Semenov, Yu. P. Gousev +1 more

We present theoretical analysis of the performance of a superconducting hot-electron bolometer mixer with electron cooling due to electron phonon interaction. The analysis is based on a complete set of thermal balance equations for phonons and electrons. A non-thermal action of a dc current has been considered phenomenologically using an analytical fit of isothermal current-voltage characteristics of the mixer. The operation point of the mixer has been determined as a result of the heating by both the power of a local oscillator and the power dissipated by the current. Electron temperature fluctuations, Nyquist noise, and shot noise have been supposed to only contribute to the mixer noise. The conversion gain and the noise temperature of the mixer have been evaluated taking into account an electro-thermal feedback between the mixer and an intermediate frequency circuit with an arbitrary impedance. We have obtained general expressions for the conversion gain, noise temperature and impedance which enabled us to estimate ultimate performance of a superconducting hot-electron bolometer mixer. Theoretical predictions are in good agreement with experimental results obtained for a NbN hot-electron bolometer mixer at a radiation frequency of 2.5 THz.

Softwaretechnik-Trends•Mar 1, 1996•21 citations

Comparison between hot spot modeling and measurement of a superconducting hot electron bolometer mixer at submillimeter wavelengths

Wei Miao, Y. Delorme, A. Féret +8 more

This paper presents the modeling and measurement of a quasioptical niobium nitride superconducting hot electron bolometer mixer at submillimeter wavelengths. The modeling is performed with a distributed hot spot model which is based on solving a heat balance equation for electron temperature along the superconducting microbridge. Particular care has been taken during the modeling concerning the temperature-dependent resistance and the bias current dependence of the critical temperature of the device. The dc and mixing characteristics of this mixer have been computed and we have observed a quite good match between the predicted and the measured results for both dc characteristics and mixing performances at submillimeter wavelengths.

Journal of Applied Physics•Nov 15, 2009•13 citations

Resistive transition of niobium superconducting hot-electron bolometer mixers

D. Wilms Floet, J. J. A. Baselmans, T. M. Klapwijk +1 more

We present a model for the description of the resistive transition in hot-electron bolometer mixers. We show that the transition is a property of a superconducting microbridge connected to normal conducting cooling pads. Using the concepts of the superconducting proximity effect, charge-imbalance generation, and Andreev reflection, we have calculated the resistance versus temperature of the device and demonstrate its dependence on the length of the microbridge, both theoretically and experimentally. The analysis reopens the question of the relationship between the resistive transition and the situation in which the device is optimally operated as a heterodyne mixer.

Applied Physics Letters•Nov 9, 1998•31 citations

Thermal time constant of Nb diffusion-cooled superconducting hot-electron bolometer mixers

D. Wilms Floet, J. R. Gao, T. M. Klapwijk +1 more

We present an experimental study of the intermediate frequency bandwidth of a Nb diffusion-cooled hot-electron bolometer mixer for different bias voltages. The measurements show that the bandwidth increases with increasing voltage. Analysis of the data reveals that this effect is mainly caused by a decrease of the intrinsic thermal time constant of the mixer and that the effect of electrothermal feedback through the intermediate frequency circuit is small. The results are understood using a qualitative model, which takes into account the different effective diffusion constants in the normal and superconducting domains.

IEEE Transactions on Applied Superconductivity•Mar 1, 2001•2 citations
We compare theoretical predictions based on the electronic hot spot (EHS) model for hot electron bolometers with experimental results obtained with a Nb diffusion-cooled bolometer. We calculate the current-voltage, I(V), characteristics both analytically and numerically and find a good agreement with unpumped and pumped experimental I(V) curves. Observed deviations can partially be explained by the thermal conductance of the superconducting parts of the microbridge, which is lower than the normal state value assumed in the analytical model. Remaining deviations are attributed to heat-trapping due to Andreev reflection, resulting in a thermal boundary resistance at the interface. Furthermore, the influence of a finite electron-electron interaction time, which prevents complete thermalization of the electrons, is discussed.
A hot spot model for superconducting hot electron bolometers is presented based on a two-dimensional heat transport equation for electrons and phonons including heat trapping due to quasiparticle bandgap gradients. Skin effect concentrates the RF heating in lateral regions of the bridge and the bias current in the center. A reduction in conversion gain compared to a one-dimensional hot spot model is explained by the RF and bias heating profiles not being identical. An experimentally verified increase of the IF bandwidth from 3.5 GHz to 8 GHz when increasing bias voltage is predicted. IV curves, gain and noise are in very good agreement with measurements.
Abstract — A hot spot mixer model for phonon cooled hot electron bolometers is set up to accurately determine the dependence of the bolometer resistance on bias and absorbed LO power. An one-dimensional power balance for the nonequilibrium electrons containing an electron heat conduction term along the film and a loss term due to phonon escape to the substrate is solved. In the device's operating region of interest the absorbed heating power is usually large enough to heat a part of the bolometer bridge above the critical temperature forming a normal conducting hot spot. In this model heating due to the LO is assumed to be uniform whereas bias heating takes place in the hot spot region only. Solving the nonlinear power balance for the hot spot length allows to predict current-voltage characteristics, required heating powers and regions of optimal operation. Applying a small signal model in a given operating point yields an estimate for the intrinsic conversion gain. I. LARGE SIGNAL MODEL Existing device models for hot electron bolometers [1,2] treat the bolometer as a lumped element. It is assigned an effective temperature for the phonons and another for the electrons at a given bath temperature. In terms of heating bias power and RF power are equivalent and exchangeable. From this a method [3,4] to calculate the absorbed RF power is derived. This method is referred to as "isotherm " method: Operating points with identical device resistance must have identical temperatures since R(To„,,(,,, ) is a single valued monotonous function. Identical temperature implies identical power losses and identical 592
We present theoretical analysis of the performance of a superconducting hot-electron bolometer mixer with electron cooling due to electron phonon interaction. The analysis is based on a complete set of thermal balance equations for phonons and electrons. A non-thermal action of a dc current has been considered phenomenologically using an analytical fit of isothermal current-voltage characteristics of the mixer. The operation point of the mixer has been determined as a result of the heating by both the power of a local oscillator and the power dissipated by the current. Electron temperature fluctuations, Nyquist noise, and shot noise have been supposed to only contribute to the mixer noise. The conversion gain and the noise temperature of the mixer have been evaluated taking into account an electro-thermal feedback between the mixer and an intermediate frequency circuit with an arbitrary impedance. We have obtained general expressions for the conversion gain, noise temperature and impedance which enabled us to estimate ultimate performance of a superconducting hot-electron bolometer mixer. Theoretical predictions are in good agreement with experimental results obtained for a NbN hot-electron bolometer mixer at a radiation frequency of 2.5 THz.
This paper presents the modeling and measurement of a quasioptical niobium nitride superconducting hot electron bolometer mixer at submillimeter wavelengths. The modeling is performed with a distributed hot spot model which is based on solving a heat balance equation for electron temperature along the superconducting microbridge. Particular care has been taken during the modeling concerning the temperature-dependent resistance and the bias current dependence of the critical temperature of the device. The dc and mixing characteristics of this mixer have been computed and we have observed a quite good match between the predicted and the measured results for both dc characteristics and mixing performances at submillimeter wavelengths.
We present a model for the description of the resistive transition in hot-electron bolometer mixers. We show that the transition is a property of a superconducting microbridge connected to normal conducting cooling pads. Using the concepts of the superconducting proximity effect, charge-imbalance generation, and Andreev reflection, we have calculated the resistance versus temperature of the device and demonstrate its dependence on the length of the microbridge, both theoretically and experimentally. The analysis reopens the question of the relationship between the resistive transition and the situation in which the device is optimally operated as a heterodyne mixer.
We present an experimental study of the intermediate frequency bandwidth of a Nb diffusion-cooled hot-electron bolometer mixer for different bias voltages. The measurements show that the bandwidth increases with increasing voltage. Analysis of the data reveals that this effect is mainly caused by a decrease of the intrinsic thermal time constant of the mixer and that the effect of electrothermal feedback through the intermediate frequency circuit is small. The results are understood using a qualitative model, which takes into account the different effective diffusion constants in the normal and superconducting domains.