Superconducting Single-photon Detectors Made of Ultra-thin VN Films

Zolotov, Philipp; Divochiy, A.; Vakhtomin, Yu. B.; Seleznev, V.; Morozov, Pavel V.; Смирнов, К. В.

doi:10.18502/ken.v3i3.2016

Cited by 7 publications

(3 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Though near perfect films can be grown on lattice MgO (100), for practical applications, growth on affordable substrates such as SiO 2 is preferred. This aspect is particularly important with respect to the upcoming applications of VN in SNSPDs. , Here, materials grown on SiO 2 are preferred as opposed to single crystalline oxide substrates that are not compatible with the fabrication of nanowire or Si substrates that are prone to metal silicide formation at high growth temperatures . In addition, as shown very recently, the intrinsic detection efficiency of disordered NbTiN films was found to be superior .…”

Section: Introductionmentioning

confidence: 99%

“…Studies indicate that VN with a chemically stoichiometric composition demonstrates an elevated T C , whereas an increase in nitrogen vacancies leads to a suppression in T C , that simultaneously leads to change in the chemical environment and lattice shrinking. ,, Notably, recent experimental results show that applying hydrostatic pressure on bulk VN up to 8 GPa can enhance the T C , suggesting the suppression of spin fluctuations, and the phonon softening in VN and their significant role in superconductivity . Superconducting thin films are of greater importance for practical applications such as superconducting quantum interference devices and superconducting nanowire single-photon detectors (SNSPDs). , Furthermore, the wide range of stoichiometry in the VN system allows a continuous variation of the density of states (DOS) at the Fermi level, by varying the metal to nonmetal ratio.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Structure and Superconductivity of Epitaxial and Polycrystalline VN Thin Films

Verma,

Gupta,

Prakash

et al. 2024

ACS Appl. Electron. Mater.

View full text Add to dashboard Cite

In this work, we present a systematic study of superconducting vanadium mononitride (VN) thin films that were simultaneously grown on single crystalline MgO (100) and amorphous SiO 2 substrates. The structure of both samples was probed using X-ray diffraction measurements under different geometries, i.e., specular, off-specular, and ϕ-scan. It was found that the lattice parameter (LP) of VN films grown on SiO 2 was 4.098(7) Å, while on MgO, it was slightly larger at 4.124(2) Å. Though the LP of both samples is within the experimentally obtained and theoretically predicted values, the obtained difference suggests that the polycrystalline VN has a tensile strain as compared to the epitaxial film. The effect of such strain is more clearly reflected on the superconducting transition temperature (T C ) and normal state electrical resistivity (ρ n ). In case of the epitaxial VN sample, the T C was at 8.1 K, while in the polycrystalline sample, it was at 5.2 K. The ρ n was also found to be significantly smaller in epitaxial films, suggesting a better crystalline quality. We performed X-ray absorption and hard X-ray photoelectron spectroscopy measurements to probe the electronic structure. It was found that the surface region of polycrystalline or epitaxial samples remains unaffected by such strains. However, high magnetic field resistivity measurements exhibited a two-step T C in the epitaxial film which originates due to formation of a thin strained region formed during the initial stages of growth. Our in situ reflection high energy electron diffraction measurements confirmed that the initial stages of growth is strained due to lattice mismatch of about +2.13% between MgO and VN. Overall, this comparative study of epitaxial and polycrystalline samples elucidates the role of stress and strain on the structural, electronic, and superconducting properties of VN thin films.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure and Superconductivity of Epitaxial and Polycrystalline VN Thin Films

Verma,

Gupta,

Prakash

et al. 2024

ACS Appl. Electron. Mater.

View full text Add to dashboard Cite

show abstract

“…First, VN is a technological material, the films of which, like many other nitrides, can be obtained by a fairly simple method of reactive magnetron sputtering of a single-element target 8 . Secondly, the advantage of VN material is its critical temperature (T c ~ 9 K) 9 ,which, on the one hand, does not require complex cryogenic equipment as for TiN, and, on the other hand, is somewhat lower than the critical temperature of the NbN or the NbTiN films, which can also be considered as an open 1 Moscow State Pedagogical University, Malaya Pirogovskaya Str. 1, Moscow 119991, Russia.…”

mentioning

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

View full text Add to dashboard Cite

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.

show abstract