Pentin Ivan, Vakhtomin Yury, Seleznev Vitaly, Smirnov Konstantin
Moscow State Pedagogical University, Malaya Pirogovskaya Str. 1, Moscow, 119991, Russia.
Superconducting Nanotechnology, LLC 5/1-14 L'va Tolstogo Str., Moscow, 119021, Russia.
Sci Rep. 2020 Oct 8;10(1):16819. doi: 10.1038/s41598-020-73850-2.
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), 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 (ω ≈ 0.140 THz) and sources in the IR region (ω ≈ 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 (ω ≈ 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 ω ≈ (0.3-6) THz VN HEB detector. The estimated values of noise equivalent power (NEP) for VN HEB and its minimum energy level (δE) reached NEP ≈ 6.3 × 10 W/√Hz and δE ≈ 8.1 × 10 J, respectively.
本文介绍了对由薄（d≈6nm）无序超导氮化钒（VN）薄膜制成的结构中电子能量弛豫动力学进行研究的实验结果，这些薄膜通过高频辐射和传输电流转变为电阻状态。在准平衡超导条件和接近临界温度（~T）的温度范围内，通过拍频法直接测量了电子的能量弛豫时间，该方法源于太赫兹以下区域（ω≈0.140太赫兹）中两个频率相近的单色源的辐射以及红外区域（ω≈193太赫兹）中的源。对所研究的VN结构在太赫兹和红外辐射加热时电子的能量弛豫时间测量结果完全一致，为（2.6 - 2.7）纳秒。对VN结构对红外（ω≈193太赫兹）皮秒激光脉冲的响应研究还使我们能够估算VN结构中的能量弛豫时间，约为2.8纳秒，与通过混频法得到的结果吻合良好。此外，我们还给出了在频率范围ω≈（0.3 - 6）太赫兹内VN热电子测辐射热计的实验测量伏瓦响应率（S）。VN热电子测辐射热计的噪声等效功率（NEP）估计值及其最低能量水平（δE）分别达到NEP≈6.3×10瓦/√赫兹和δE≈8.1×10焦耳。
