Electron–Phonon Energy Relaxation Time in Thin Strongly Disordered Titanium Nitride Films

Кардакова, А. И.; Coumou, P. C. J. J.; Finkel, Matvey; Morozov, D.; An, Pavel; Gol’tsman, G.; Klapwijk, T. M.

doi:10.1109/tasc.2014.2364516

Cited by 9 publications

(7 citation statements)

References 27 publications

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“…The low value of ξ (0) is suspected to be caused by disorder in the sputtered films, where the renormalization due to short electronic mean free path l is approximatelly ξ * = 0.85 ξ × l 30 . If we assume unpreturbed ξ = 105 nm 31 , we end up with mean free path of approximately 4 Å, which is within the reported range [3.5-7.3] Å for TiN 32 . Many applications of superconducting devices often require the material to be in the form of a thin film.…”

Section: Resultssupporting

confidence: 77%

Ion-beam Assisted Sputtering of Titanium Nitride Thin Films

Draher

Polakovic

et al. 2022

Preprint

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Titanium nitride is a material of interest for many superconducting devices such as nanowire microwave resonators and photondetectors. Thus, controlling the growth of TiN thin films with desirable properties is of high importance. This work aims toexplore effects in ion beam-assisted sputtering (IBAS), which has reduced nitrogen sensitivity during deposition in tandemwith an increase in nominal critical temperature and upper critical fields in previous work on Niobium nitride (NbN). We growthin films of titanium nitride by both, the conventional method of DC reactive magnetron sputtering and the IBAS method, tocompare their superconducting critical temperatures Tc as functions of thickness, sheet resistance, and nitrogen flow rate.We perform electrical and structural characterizations by electric transport and x-ray diffraction measurements. Comparedto the conventional method of reactive sputtering, the IBAS technique has demonstrated a 10% increase in nominal criticaltemperature and 33% reduced sensitivity to nitrogen flow, without noticeable variation in the lattice structure. Additionally, weexplore the behavior of superconducting Tc in ultra-thin films. Trends in films grown at high nitrogen concentrations followpredictions of mean-field theory in disordered films and show suppression of superconducting Tc due to geometric effects,while nitride films grown at low nitrogen concentrations strongly deviate from the theoretical models.

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Section: Resultssupporting

confidence: 77%

Ion-beam Assisted Sputtering of Titanium Nitride Thin Films

Draher

Polakovic

et al. 2022

Preprint

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“…A distinctive feature of this sample was a slightly increased value of the temperature of the transition to the superconducting state (6 K versus 5.6 K), which most likely led to some shortening of the electron–phonon interaction. Numerous experimental studies of the electron–phonon interaction time (τ e-ph ) in nitride-based compounds show that this time in a similar temperature range exhibits a dependence of the form τ ~ T −n , where T is the temperature at which time is measured (τ e-ph ), n is power exponent, which typically takes the value from ~ 1.6 to ~ 3 (n = 1.6 for NbN 20 , n = 3 for TiN 6 ). Then the extrapolated relaxation time value (τ) based on the expression gives the value from τ ~ 2.3 ns to τ ~ 2.1 ns, which is in good agreement with the measured value τ ≈ 2.1 ns.…”

Section: Investigation Of the Energy Relaxation Time Of Electrons In mentioning

confidence: 99%

“…In addition to NbN films, when studying the effects of non-equilibrium superconductivity and developing receiving devices, nitrides of other transition metals are often used. For example, in the works 7 the results of studies of thin TiN films having lower operating temperatures compared to NbN were demonstrated and the possibilities of creating detectors based on them were show.…”

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confidence: 99%

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

Pentin

Vakhtomin

Seleznev

et al. 2020

Sci Rep

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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 (~ Tc), 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@1MHz ≈ 6.3 × 10–14 W/√Hz and δE ≈ 8.1 × 10–18 J, respectively.

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“…This condition can be achieved in typical superconductors, where the two time scales are well-separated at low temperature 72 , with τ e−e order of magnitude smaller 72 than the τ e−ph . For example, below 0.1T c , τ e−ph can range from ∼ 100ns of niobiumbased superconductors 73,74 to ∼ 10 1 ÷ 10 2 µs of aluminium or tantalum thin films 46,75 , while τ e−e is about 1 ÷ 10ns 6 . Then iso-entropic processes are possible with phase-switching rates in the window 10 ÷ 10 3 MHz.…”

Section: Possible Experimental Implementationsmentioning

confidence: 99%

Coherent Josephson thermodynamic cycles

Vischi,

Carrega,

Virtanen

et al. 2018

Preprint

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A superconductor/normal metal/superconductor Josephson junction is a coherent electron system where the thermodynamic entropy depends on temperature and phase difference across the weak-link. Here, exploiting the phase-temperature thermodynamic diagram of a thermally isolated system, we argue that a cooling effect can be achieved when the phase drop across the junction is brought from 0 to π in a iso-entropic process. We show that iso-entropic cooling can be enhanced with proper choice of geometrical and electrical parameters of the junction, i.e. by increasing the ratio between supercurrent and total junction volume. We present extensive numerical calculations using quasi-classical Green function methods for a short junction and we compare them with analytical results. Interestingly, we demonstrate that phase-coherent thermodynamic cycles can be implemented by combining iso-entropic and iso-phasic processes acting on the weak-link, thereby engineering the coherent version of thermal machines such as engines and cooling systems. We therefore evaluate their performances and the minimum temperature achievable in a cooling cycle.

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Electron–Phonon Energy Relaxation Time in Thin Strongly Disordered Titanium Nitride Films

Cited by 9 publications

References 27 publications

Ion-beam Assisted Sputtering of Titanium Nitride Thin Films

Ion-beam Assisted Sputtering of Titanium Nitride Thin Films

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

Coherent Josephson thermodynamic cycles

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