YBa2Cu3O7-δ Thin Film Growth on Different Substrates by Pulsed Laser Deposition (original) (raw)
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Journal of Superconductivity and Novel Magnetism, 2013
In this paper, the influence of oxygen pressure on film quality and superconducting properties of YBa 2 Cu 3 O 7−δ (YBCO-Y123) thin films prepared by Pulsed Laser Deposition (PLD) was investigated. For this purpose, YBCO thin films were deposited on polished LaAlO 3 (l00) (LAO) substrates at three different oxygen pressures (150, 200, and 250 mTorr). X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques were used to make comparative studies of film microstructure. Except for oxygen pressures, all other variables such as number of pulses, repetition rate, deposition temperature, heating and cooling rate, target-substrate distance, laser excitation energy, annealing temperature, and annealing pressure were fixed. For this fixed set of parameters, SEM, XRD analysis, and AC susceptibility measurements of these films revealed that the crystal structure quality and superconducting properties of YBCO thin films are optimum at the oxygen deposition pressure of 150 mTorr. As the deposition pressure increased, Y 2 BaCuO 5 (Y211) phase peaks were seen in XRD patterns. The reason for this was believed to be caused by decreased concentration of CuO and BaO as determined by Energy Dispersive X-Ray Spectroscopy (EDX) of thin films.
Applied Surface Science, 1998
Ž. Ž. Ž. YBCO superconducting films were deposited by XeCl s 308 nm pulsed laser deposition PLD on 100-oriented SrTiO , MgO and Si single crystal substrates. Control of the YBCO thin film epitaxial growth and microstructure quality are 3 important factors for superconducting electronic device applications. In this aim, we studied the influence of the oxygen pressure during the growth, the distance between target-substrate and substrate structure on the degree of structural Ž. Ž. orientation and surface quality of the films. X-ray diffraction XRD , scanning electron microscopy SEM and atomic force Ž. microscopy AFM techniques were used to make comparative studies of microstructure with transport properties of the films. q 1998 Elsevier Science B.V.
Growth mechanism and properties of YBa2Cu3O7 thin films deposited by laser ablation on (001) SrTiO3
Revista Romana de materiale = Romanian journal of materials = RRM
High quality, single phase c-axis oriented YBa2Cu3O7-δ thin films with superconducting properties were grown by laser ablation on (001) SrTiO3 substrates. The surface morphology of the films has been investigated by means of high-pressure reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), and scanning electron microscopy (SEM), while the structural properties were studied by X-ray diffraction (XRD). Deposition under optimum conditions produces films with relatively smooth surface, with a roughness of about 10-15 nm, as confirmed by AFM and SEM data. The growth follows a Stransky-Krastanov mechanism governed by the substrate-film interface properties due to presence of epitaxial strain. The films show good superconducting properties with Tc values of 85-91 K. Preliminary data on transport properties of YBa2Cu3O7-δ based ramp-type Josephson junction with a PrBa2Cu3O7-δ barrier are presented in the last part of the paper.
Il Nuovo Cimento D, 1997
We have studied the superconducting and structural properties of YBCO thin films and YBCO/STO/YBCO trilayers deposited on (100) SrTiO3 substrates by off-axis PLD technique. The as-obtainedc-axis oriented YBCO films show an excellent surface free of droplets or other irregularities as well as good structural and superconducting properties with Tc (R=0)=89 K, Jc=3×106 A/cm2 (at 77 K and zero magnetic field) and the Full Width at Half Maximum (FWHM) of the (005) YBCO rocking curve of about 0.2°. These structural and electrical properties are very close to those of the YBCO films deposited by the conventional PLD on-axis geometry. The TEM cross-sectional image shows that the YBCO/STO/YBCO heterostructure has smooth interfaces and no short-circuits or pinholes were observed. The electron diffraction analysis has revealed that both YBCO top and bottom layer as well as STO interlayer are epitaxially grown withc-axis perpendicular to the substrate.
Superconducting YBa2Cu3O7 films grown on TiO2 buffer layers derived from various processes
Physica C: Superconductivity, 2001
YBa 2 Cu 3 O 7 (YBCO)/TiN and YBCO/TiO 2 bilayer structures have been prepared on SrTiO 3 (STO)(1 0 0) substrates by in situ pulsed laser deposition (PLD). The TiN ®lms were originally intended to serve as the lower contact electrode for studying the c-axis transport properties of YBCO thin ®lms. It was found that, under the optimum conditions of depositing YBCO thin ®lms, the TiN(1 0 0) layer was oxidized and transformed into rutile TiO 2 (1 1 0) ®lm. On the other hand, pure anatase TiO 2 (0 0 1) ®lms were prepared by PLD using a rutile TiO 2 (1 1 0) substrate as the target. YBCO ®lms grown on both phases of TiO 2 ®lms show virtually the same transport properties of typical good quality singlelayer YBCO ®lms. Comparative studies of depositing YBCO ®lms directly onto a dc-sputtered TiO 2 template commonly used in the selective epitaxial growth process have, however, resulted in formation of a nonsuperconducting YBCO top layer. Experiments including interfacial X-ray absorption spectroscopy for determining the possible interactions occurring at the YBCO and TiO 2 interface are reported. Ó
Early stages of growth of YBa2Cu3O7−δ high Tc superconducting films on (001) Y-ZrO2 substrates
Journal of Applied Physics, 1994
The early stages of growth of high quality YBa2Cu307--6 (YBCO) films grown on (001) Y-ZrOa (YSZ) substrates by pulsed laser deposition have been studied using a combination of atomic force microscopy and transmission electron microscopy. A one unit cell thick YBCO layer and relatively large CuO particles formed in the initial stages. Additional YBCO grew on top of the first laier in the form of one or a few unit cell high c-axis oriented islands about 30 nm in diameter. The rounded islands subsequently coalesced into faceted domains. Elongated Y,BaCuO, particles nucleated after the first layer of YBCO. A highly textured BaZrO, layer formed between the YSZ and the YBCO with a cube-on-cube dominant orientation relationship with respect to the YBCO film.
Journal of Superconductivity, 1997
Superconducting YBa2CuI0, thin lilms were deposited on NJGa03 (I IO) substrates using two dilTcrcnt techniques: dc sputtering at high oxygen pressure and pulsed laser deposition The structure. electrical propertics. and surface morphology of the obtained films were COIW pared. The superior crystal quality of dc-sputtered lil111s fabricated at the same tcmpcraturc and :lt oxygen pressure of the smne range as for laser-deposited lihns can be explained by :I lower deposition rate providing time [or recrystallization processes. The rc-cvaporatlon be~~uncs significant for dc sputtering at hi$ deposition temperatures and results 111 Ba-Jcticicnt lilms. The high mobility of atoms on the surface of the growing film during I;ISCI dcpozltion helps in ~hc formation of smooth c-oriented arcas of the film.