Hot electron energy relaxation time in vanadium nitride superconducting film structures under THz and IR radiation.

ABSTRACT: The paper presents the experimental results of studying the dynamics of electron energy relaxation in structures made of thin (d???6 nm) disordered superconducting vanadium nitride (VN) films converted to a resistive state by high-frequency radiation and transport current. Under conditions of quasi-equilibrium superconductivity and temperature range close to critical (~?T_c), a direct measurement of the energy relaxation time of electrons by the beats method arising from two monochromatic sources with close frequencies radiation in sub-THz region (? ? 0.140 THz) and sources in the IR region (? ? 193 THz) was conducted. The measured time of energy relaxation of electrons in the studied VN structures upon heating of THz and IR radiation completely coincided and amounted to (2.6-2.7) ns. The studied response of VN structures to IR (? ? 193 THz) picosecond laser pulses also allowed us to estimate the energy relaxation time in VN structures, which was?~?2.8 ns and is in good agreement with the result obtained by the mixing method. Also, we present the experimentally measured volt-watt responsivity (S_~) within the frequency range ? ? (0.3-6) THz VN HEB detector. The estimated values of noise equivalent power (NEP) for VN HEB and its minimum energy level (?E) reached NEP_@1MHz ? 6.3?×?10^-14 W/?Hz and ?E ? 8.1?×?10^-18 J, respectively.

SUBMITTER: Pentin I 

PROVIDER: S-EPMC7546726 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature