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Quantum Efficiency of Cold Electron Bolometer Optical Response

Mikhail Tarasov (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Valerian S. Edelman ; Andrey B. Ermakov ; Sumedh Mahashabde (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik) ; Leonid Kuzmin (Institutionen för mikroteknologi och nanovetenskap, Kvantkomponentfysik)
IEEE Transactions on Terahertz Science and Technology (2156-342X). Vol. 5 (2014), 1, p. 44-48.
[Artikel, refereegranskad vetenskaplig]

In this paper we present the measurements of optical response dependence on power load of a Cold Electron Bolometer integrated in a twin slot antenna. These measurements are also compared to the models of the bolometer limit and the photon counter limit. The responsivity of 0.22*10^9 V/W was measured at 0.22 pW radiation power from a black body at 3.5 K. According to our estimations, for optimized device the voltage responsivity at 100 mK electron temperature can approach Sv=10^10 V/W for power load below 0.1 pW and decreases down to 10^7 V/W at 300 mK for 5 pW signal power in a sample with absorber volume of 5*10^-20 m^3. In the case of low bath temperatures and high applied RF power the changes of tunneling current, dynamic resistance and voltage response are explained by non-thermal energy distribution of excited electrons. Distribution of excited electrons in such system at lower temperatures can be of non-Fermi type, hot electrons with energies of the order of 1 K tunnel from normal metal absorber to superconductor instead of relaxing down to thermal energy kTe in absorber before tunneling. This effect can reduce quantum efficiency of the bolometer at 350 GHz from hf/kTph>100 in ideal case down to single electron per absorbed photon (Q.Eff=1) in the high power case. Methods of preserving high quantum efficiency are discussed.

Nyckelord: bolometers, nanofabrication, slot antennas, submillimeter wave technology, superconducting devices



Denna post skapades 2014-12-15. Senast ändrad 2015-12-17.
CPL Pubid: 208134

 

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