Mechanisms of cation defect formation in epitaxial YBa2Cu3O7−x films

Берт, Н. А.; Lunev, A. V.; Musikhin, Yu. G.; Suris, R. A.; Tret’yakov, V. V.; Bobyl, A. V.; Karmanenko, S. F.; Dedoborez, A.I.

doi:10.1016/s0921-4534(97)00112-3

Cited by 6 publications

(6 citation statements)

References 33 publications

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“…Raman spectra were excited by an Ar laser and measured by a spectrometer based on a double monochromator. To determine the composition of YBCO films, microanalysis of the lines Y L α , Ba L α , Cu K α , Cu L α and O K α was carried out using an x-ray 'Camebax' microanalyser [31]. The film morphology was studied with a CamScan Series 4-88 DV100 automated scanning electron microscope.…”

Section: Film Growth and Diagnostics Of Ybco Filmsmentioning

confidence: 99%

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Karmanenko

Семенов

Khrebtov

et al. 2000

Supercond. Sci. Technol.

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An analysis of how the detectivity and lifetime depend on the fabrication process of superconducting antenna-coupled microbolometers has been carried out. The temperature dependences of responsivity and noise equivalent power (NEP) have been estimated in terms of the thermal model. To reveal the main degradation mechanism, 1/f-noise characterization has been used. Monte-Carlo simulation of the annealing procedure of YBa 2 Cu 3 O 7 (YBCO) films for the operating ranges of frequency and temperature has shown that prevailing sources of flicker noise in superconducting microstrips are associated with transitions of oxygen atoms situated close to low-angle boundaries of the film blocks. The magnetron sputtering technique has been optimized to reduce the Hooge parameter for flicker noise to a record-breaking low value for YBCO films of about 10 −4 at 93 K. Comparative analysis of chemical, ion and laser etching techniques by low-temperature scanning electron microscopy and magneto-optics allowed the fabrication of microstrips with uniform current distribution characterized by critical current density higher than 10 6 A cm −2 at 77 K and long-time stability. The process of low-energy ion milling of YBCO films with an Ar + beam generated in a duopigatron ion source was used to reach a width resolution at the topology edge better than 0.2 µm. The antenna-coupled bolometers fabricated from the superconducting microstrips were used to register microwave radiation at a frequency of 70.3 GHz and temperature of 93 K. It is demonstrated that the developed technology makes possible the fabrication of long-lived YBCO-based antenna microbolometers with electrical NEP e = 1.5 × 10 −12 W Hz −1/2. The calculated response time of the antenna is about 30-150 ns. Further development is associated with fabrication of coupling microbolometers with immersed lens, with predicted optical detectivity D * = (4 × 10 9 −4 × 10 10) cm Hz 1/2 W −1 in the wavelength range 100-1000 µm.

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Section: Film Growth and Diagnostics Of Ybco Filmsmentioning

confidence: 99%

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Karmanenko

Семенов

Khrebtov

et al. 2000

Supercond. Sci. Technol.

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“…2 The electron energy in the exciting beam was 15 keV which allowed us to register simultaneously the spectral lines Y L␣, Ba L␣, Cu K␣, and O K␣ for all the elements, and determine the film thickness in the same experiment. The absolute accuracy of the chemical composition determination is 0.3%, 1.0%, 1.2%, and 2.0% for Y, Ba, Cu and O, respectively.…”

Section: B Quantitative Electron Probe Microanalysismentioning

confidence: 99%

“…A uniform oxygen distribution in YBa 2 Cu 3 O 7Ϫ␦ films has also been observed earlier. 1,2 It is probably a consequence of a high diffusion coefficient of oxygen in the YBa 2 Cu 3 O 7Ϫ␦ lattice. Thus, we can focus on variations in the cation composition only.…”

Section: A Chemical Composition Variationmentioning

confidence: 99%

“…Analysis of the correlation between locally measured cation composition, critical temperature, and flicker noise allowed the development of a theoretical model for cation defect formation in YBa 2 Cu 3 O 7 films. 2 Spatial distribution of the critical current density, j c , is also of great interest. It is a quantity that is important for both HTSC applications and for understanding the pinning mechanisms.…”

Section: Introductionmentioning

confidence: 99%

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Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Gaevski

Bobyl

Shantsev

et al. 1998

Journal of Applied Physics

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Spatially-resolved studies of a YBa2Cu3O 7−δ thin film bridge using electron probe microanalysis (EPMA), low-temperature scanning electron microscopy (LTSEM), and magneto-optical flux visualization (MO) have been carried out. Variations in chemical composition along the bridge were measured by EPMA with 3 µm resolution. Using LTSEM the spatial distributions of the critical temperature, Tc, and of the local transition width, ∆Tc, were determined with 5 µm resolution. Distributions of magnetic flux over the bridge in an applied magnetic field have been measured at 15 and 50 K by magneto-optical technique. The critical current density jc as a function of coordinate along the bridge was extracted from the measured distributions by a new specially developed method. Significant correlations between jc, Tc, ∆Tc and cation composition have been revealed. It is shown that in low magnetic fields deviation from the stoichiometric composition leads to a decrease in both Tc and jc. The profile of jc follows the Tc-profile on large length scales and has an additional fine structure on short scales. The profile of jc along the bridge normalized to its value at any point is almost independent of temperature.

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“…This origin can be dominant in thin YBCO films, as shown by simultaneous spatially resolved studies of cation composition and T c using electron probe microanalysis and low-temperature scanning electron microscopy (LTSEM), respectively. 4,5 Elastic stresses around structural defects can also lead to T cinhomogeneity due to a strong pressure dependence of T c in HTSC compounds. 6 T c increase due to edge dislocations and low-angle grain boundaries was calculated to be ∼ 1 K. 7 Spatial variations of the c-axis lattice parameter revealed by x-ray studies in YBCO films with almost uniform oxygen content also suggest stress-induced T cinhomogeneity.…”

Section: Introductionmentioning

confidence: 99%

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
7
0
7
0
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Temperature and magnetic-field dependence of the conductivity of YBa 2 Cu 3 O 7−δ films in the vicinity of superconducting transition: Effect of T C -inhomogeneity Temperature and magnetic field dependences of the conductivity of YBa2Cu3O 7−δ films in the transition region are analyzed taking into account spatial inhomogeneity in transition temperature, Tc. (i) An expression for the superconducting contribution to conductivity, σs(T, H, Tc), of a homogeneous superconductor for low magnetic fields, H ≪ Hc2 (0) (ii) The error in σs(T, H, Tc) occurring due to the presence of Tc-inhomogeneity is calculated and plotted on an H − T plane diagram. These calculations use an effective medium approximation and a Gaussian distribution of Tc. (iii) Measuring the temperature dependences of a voltage, induced by a focused electron beam, we determine spatial distributions of the critical temperature for YBa2Cu3O 7−δ microbridges with a 2 µm resolution. A typical Tc-distribution dispersion is found to be ≈1 K. For such dispersion, error in σs(T, H, Tc) due to Tc-inhomogeneity exceeds 30% for magnetic fields H < 1 T and temperatures |T − Tc| < 0.5 K . (iv) Experimental R(T, H) dependences of resistance are well described by a numerical solution of a set of Kirchoff equations for the resistor network based on the measured spatial distributions of Tc and the expression for σs(T, H, Tc).

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Mechanisms of cation defect formation in epitaxial YBa2Cu3O7−x films

Cited by 6 publications

References 33 publications

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
7
0
7
0
View full text Add to dashboard Cite

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Mechanisms of cation defect formation in epitaxial YBa2Cu3O7−x films

Cited by 6 publications

References 33 publications

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Fabrication process and noise properties of antenna-coupled microbolometers based on superconducting YBCO films

Spatially resolved studies of chemical composition, critical temperature, and critical current density of a YBa2Cu3O7−δ thin film

Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3OShantsev1, Gaevski2, Suris3 et al. 1999Phys. Rev. B7070View full textAdd to dashboardCite

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Temperature and magnetic-field dependence of the conductivity ofYBa2Cu3O
Shantsev
¹
,
Gaevski
²
,
Suris
³

et al. 1999
Phys. Rev. B
7
0
7
0
View full text Add to dashboard Cite