Title :
A two-dimensional hot-spot mixer model for phonon-cooled hot electron bolometers
Author :
Merkel, Harald F. ; Khosropanah, Pourya ; Cherednichenko, Serguei ; Yngvesson, K. Sigfrid ; Adam, Aurèle ; Kollberg, Erik L.
Author_Institution :
Chalmers Univ. of Technol., Goteborg, Sweden
fDate :
3/1/2001 12:00:00 AM
Abstract :
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
Keywords :
bolometers; electron-phonon interactions; heat transfer; hot carriers; niobium compounds; quasiparticles; radiofrequency heating; skin effect; submillimetre wave mixers; superconducting device noise; superconducting microwave devices; superconducting mixers; temperature distribution; 3.5 to 8 GHz; 600 GHz to 2.5 THz; IF bandwidth; IV curves; NbN; RF heating concentration; bias heating profiles; bias voltage; conversion gain; gain; heat trapping; lateral regions; noise; phonon-cooled hot electron bolometers; quasiparticle bandgap gradients; skin effect; superconducting hot electron bolometers; two-dimensional heat transport equation; two-dimensional hot-spot mixer model; Bandwidth; Bolometers; Bridge circuits; Electron traps; Equations; Heating; Phonons; Photonic band gap; Radio frequency; Skin effect;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
