scholarly journals Effects of the Surface Morphology of Thick CeO2 Buffer Layers on Superconducting Properties and Crystal Growth of EuBa2Cu3O7-.DELTA. Thin Films on R-Al2O3 Substrates

2006 ◽  
Vol 41 (5) ◽  
pp. 193-199 ◽  
Author(s):  
Yasuyuki OTA ◽  
Jun SAKUMA ◽  
Yutaka KIMURA ◽  
Osamu MICHIKAMI
Keyword(s):  
Thin Films ◽  
Crystal Growth ◽  
Surface Morphology ◽  
Buffer Layers ◽  
Superconducting Properties

Superconducting properties and surface morphology of SmBa2Cu3O6+δ thin films

2001 ◽  
Vol 357-360 ◽  
pp. 1358-1360 ◽  
Author(s):  
Kimihiko Sudoh ◽  
Yutaka Yoshida ◽  
Noriaki Matsunami ◽  
Yoshiaki Takai
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Superconducting Properties

Improved Epitaxy and Surface Morphology in YBa2Cu3Oy Thin Films Grown on Double Buffered Si Wafers

2003 ◽  
Vol 17 (18n20) ◽  
pp. 3695-3697 ◽  
Author(s):  
J. Gao ◽  
L. Kang ◽  
H. Y. Wong ◽  
Y. L. Cheung ◽  
J. Yang
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Large Range ◽  
Superconducting Films ◽  
Buffer Layers ◽  
Epitaxial Thin Films ◽  
Average Surface Roughness ◽  
X Ray ◽  
Flat Interface ◽  
The Eu

Highly epitaxial thin films of YBCO have been obtained on silicon wafers using a Eu 2 CuO 4/ YSZ (yttrium-stabilized ZrO 2) double buffer. Our results showed that application of such a double buffer can significantly enhance the epitaxy of grown YBCO. It also leads to an excellent surface morphology. The average surface roughness was found less than 5 nm in a large range. The results of X-ray small angle reflection and positron spectroscpy demonstrate a very clear and flat interface between YBCO and buffer layers. The Eu 2 CuO 4/ YSZ double buffer could be promising for coating high-TC superconducting films on various reactive substrates.

Epitaxial cerium oxide buffer layers and YBa2Cu3O7−δ thin films for microwave device applications

1999 ◽  
Vol 14 (6) ◽  
pp. 2385-2393 ◽  
Author(s):  
Sissel N. Jacobsen ◽  
Lynnette D. Madsen ◽  
Ulf Helmersson
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Rf Magnetron Sputtering ◽  
Sample Surface ◽  
Columnar Structure ◽  
Buffer Layers ◽  
Ex Situ ◽  
Epitaxial Relationship ◽  
Cross Sectional ◽  
Appreciable Change

CeO2 films with thicknesses ranging from 8.8 to 199 nm were grown on Al2O3 (1102) (R-cut) substrates by off-axis rf magnetron sputtering. X-ray diffraction showed an epitaxial relationship with the CeO2 (001) planes parallel to the Al2O3 (1102) planes for all film thicknesses. Atomic force microscopy (AFM) revealed a rough surface morphology consisting of crystallites with lateral dimensions of 10–90 nm. In the thinnest film, these crystallites were regularly shaped and uniformly distributed on the substrate, while they were rectangularly shaped and oriented mainly in two directions, orthogonal to each other, in the thicker films. The surface roughness of the films increased with increasing layer thickness. Characterization of the microstructure was done by cross-sectional transmission electron microscopy (XTEM) and showed a polycrystalline, highly oriented, columnar structure with a top layer terminated by (111)-facets. High-quality YBa2Cu3O7−δ (YBCO) thin films were deposited directly onto the CeO2 layers. XTEM, rather surprisingly, showed a smooth interface between the YBCO and CeO2 layer. Postdeposition ex situ annealing was carried out on two CeO2 films and evaluated by AFM. Upon annealing samples at 930 °C, a relatively smooth morphology without facets was obtained. Annealing films at 800 °C caused no appreciable change in surface morphology, whereas igniting a YBCO plasma during a similar anneal clearly altered the sample surface, giving facets that were rounded.

Epitaxial Relationships of the a-Axis Oriented YBa2Cu3O7-x Thin Films on the PrBa2Cu3O7-xTx Buffered SrTiO3(100) by two Step PLD

1994 ◽  
Vol 341 ◽  
Author(s):  
Gun Yong Sung ◽  
Jeong Dae Suh ◽  
Sahn Nahm
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Volume Fraction ◽  
Buffer Layers ◽  
Laser Deposition ◽  
Superconducting Properties ◽  
Ybco Thin Film ◽  
Axis Orientation ◽  
Ybco Thin Films ◽  
Zero Resistance

AbstractAn a-axis oriented YBa2Cu3O7-x (YBCO) thin film exhibiting zero resistance at 83 K and critical current density of 7.9x103 A/cm2 at 62 K was obtained on an 180 nm - thick PrBa2Cu3 O7-xx(PBCO) buffered SrTiO3(100) substrate by two step pulsed laser deposition (PLD). The volume fraction of a-axis orientation and the crystallinity(Xmin) of the 150 nm-thick YBCO thin films were increased with increasing the thickness of PBCO buffer layer, which was varied friom 0 nm to 180 nm. It is concluded that the thickness of PBCO buffer layer is one of the important parameters to control the structural and superconducting properties of the a-axis oriented YBCO thin films using the PBCO buffer layers.

Chemical Bath Deposition of ZnS Buffer Layers

2013 ◽  
Vol 813 ◽  
pp. 435-439
Author(s):  
Tai Quan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Light Scattering ◽  
Surface Morphology ◽  
Chemical Bath Deposition ◽  
Buffer Layers ◽  
Thin Film Solar Cells ◽  
Process Conditions ◽  
Magnetic Stirring ◽  
Light Loss

Chemical bath deposited ZnS thin films are promising buffer layers for thin film solar cells, replacing the environmentally hostile CdS buffer layers currently in use. Reflection, absorption and scattering are the three main light loss mechanisms in buffer layers. In this work, improved process conditions, such as magnetic stirring and air annealing, are used in the chemical bath deposition of ZnS thin films to optimize their surface morphology, which effectively reduces light scattering and increases the transmittance, resulting much better ZnS thin films.

PREPARATION OF BUFFER LAYERS ON SAPPHIRE FOR HIGH Tc SUPERCONDUCTING THIN FILMS

1991 ◽  
Vol 05 (19) ◽  
pp. 1267-1273 ◽  
Author(s):  
X. D. WU ◽  
R. E. MUENCHAUSEN
Keyword(s):  
Thin Films ◽  
High Frequency ◽  
Dielectric Constants ◽  
Buffer Layers ◽  
Processing Temperature ◽  
Superconducting Thin Films ◽  
Superconducting Properties ◽  
Stabilized Zirconia ◽  
Low Loss ◽  
High Tc

Sapphire is a preferred substrate for high frequency applications where small dielectric constants and low loss tangents are required. It is also much cheaper than other oxide subsrates such as SrTiO 3, LaAlO 3, NdGaO 3, MgO, and yttria-stabilized zirconia (YSZ) for high T c superconducting thin films. Unfortunately, sapphire is not chemically compatible with the high T c superconductors at the processing temperature required to obtained good superconducting properties. As a result, an appropriate buffer layer on sapphire is required.

Solid Phase Epitaxial Recrystallization of AlN Films on Sapphire (0001): A Novel Substrate Approach for GaN Epitaxy

1999 ◽  
Vol 587 ◽  
Author(s):  
R. D. Vispute ◽  
A. Patel ◽  
R. P. Sharma ◽  
T. Venkatesan ◽  
T. Zheleva ◽  
...  
Keyword(s):  
Thin Films ◽  
Surface Morphology ◽  
Lattice Mismatch ◽  
Defect Density ◽  
Solid Phase ◽  
Substantial Reduction ◽  
Inert Atmosphere ◽  
Buffer Layers ◽  
Large Defect ◽  
Defect Densities

AbstractHigh quality and lattice matched buffer layers are needed for the growth of device quality GaN thin films on sapphire for optoelectronic applications. In this context, we report the fabrication of AlN thin films having low defect densities through a novel process called solid phase epitaxial recrystallization (SPER). In this process, as-grown crystalline AlN thin films, having a large defect concentration (such as threading dislocations due to a large lattice mismatch between AlN and sapphire and low angle grain boundaries), were thermally annealed in an inert atmosphere at various temperatures ranging from 1200-1600° for 30 min. The as-grown and annealed samples were characterized using x-ray diffraction, transmission electron microscopy (TEM), Rutherford backscattering spectroscopy (RBS), atomic force microscopy (AFM) and UV-visible spectroscopy. The ion channeling/RBS and TEM results clearly indicate a substantial reduction in the defect density for the recrystallized AlN films. The surface morphology of the SPER AlN films was smooth with a surface roughness close to the unit cell height. The optical bandgap was sharp as compared to as-grown films, with a bandgap of 6.2 eV. The recrystallized films having smooth surface morphology and low defect densities may be useful for the growth of device quality GaN films on sapphire.

{10} edge dislocations in YSZ films grown on (100)MgO by PLD

1994 ◽  
Vol 52 ◽  
pp. 530-531
Author(s):  
Jason R. Heffelfinger ◽  
C. Barry Carter
Keyword(s):  
Thin Films ◽  
Semiconductor Lasers ◽  
Vapor Deposition ◽  
Substrate Surface ◽  
Laser System ◽  
Average Energy ◽  
Target Material ◽  
Chemical Vapor ◽  
Buffer Layers ◽  
Organic Chemical

Yttria-stabilized zirconia (YSZ) is currently used in a variety of applications including oxygen sensors, fuel cells, coatings for semiconductor lasers, and buffer layers for high-temperature superconducting films. Thin films of YSZ have been grown by metal-organic chemical vapor deposition, electrochemical vapor deposition, pulse-laser deposition (PLD), electron-beam evaporation, and sputtering. In this investigation, PLD was used to grow thin films of YSZ on (100) MgO substrates. This system proves to be an interesting example of relationships between interfaces and extrinsic dislocations in thin films of YSZ.In this experiment, a freshly cleaved (100) MgO substrate surface was prepared for deposition by cleaving a lmm-thick slice from a single-crystal MgO cube. The YSZ target material which contained 10mol% yttria was prepared from powders and sintered to 85% of theoretical density. The laser system used for the depositions was a Lambda Physik 210i excimer laser operating with KrF (λ=248nm, 1Hz repetition rate, average energy per pulse of 100mJ).

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