Microstructure of YBCO and YBCO/SrTiO3/YBCO PLD Thin Films on Sapphire for Microwave Applications

1999 ◽  
Vol 603 ◽  
Author(s):  
M. Lorenz ◽  
H. Hochmuth ◽  
D. Natusch ◽  
T. Thärigen ◽  
V. L. Svetchnikov ◽  
...  
Keyword(s):  
Thin Films ◽  
Cross Sections ◽  
Communication Systems ◽  
Deposition Process ◽  
Microwave Filters ◽  
Buffer Layers ◽  
Large Area ◽  
Growth Defects ◽  
Sapphire Substrates ◽  
High Degree

AbstractA large-area pulsed laser deposition process for high-quality YBa2Cu3O7−δ (YBCO) thin films on both sides of R-plane sapphire substrates with CeO2 buffer layer is used routinely to optimize planar microwave filters for satellite and mobile communication systems. With the experience of more than 700 double-sided 3-inch diam. YBCO:Ag films a high degree of reproducibility of jc values above 3.5 MA/cm2 and of state of the art R5 values is reached. TEM cross sections of the large-area and double-sided PLD-YBCO:Ag thin films on R-plane sapphire with CeO2 buffer layers show typical defects like stress modulation, stacking faults, a-axis oriented grains, precipitates and interdiffusion layers. YBCO films on SrTiO3 / YBCO* / CeO2 film systems on R-plane sapphire wafers have more growth defects compared to bare CeO2 buffers on sapphire but show as microwave resonators encouraging electrical tunability.

Growth of corundum-structured In2O3 thin films on sapphire substrates with Fe2O3 buffer layers

2013 ◽  
Vol 364 ◽  
pp. 30-33 ◽  
Author(s):  
Norihiro Suzuki ◽  
Kentaro Kaneko ◽  
Shizuo Fujita
Keyword(s):  
Thin Films ◽  
Buffer Layers ◽  
Sapphire Substrates

Cerium oxide (CeO2) buffer layers for preparation of high-Jc YBCO films on large-area sapphire substrates (30 cm×10 cm) by coating pyrolysis

2004 ◽  
Vol 412-414 ◽  
pp. 1326-1330 ◽  
Author(s):  
M. Sohma ◽  
I. Yamaguchi ◽  
K. Tsukada ◽  
W. Kondo ◽  
S. Mizuta ◽  
...  
Keyword(s):  
Cerium Oxide ◽  
Buffer Layers ◽  
Large Area ◽  
Ybco Films ◽  
Sapphire Substrates

Structural and Electrical Properties of BiFeO3 Fabricated on C-Sapphire Substrates Using a Double SrTiO3/TiO2 Buffer Layer

2011 ◽  
Vol 687 ◽  
pp. 385-390
Author(s):  
Xiu Wei Liao ◽  
Jun Zhu ◽  
Wen Bo Luo ◽  
Lan Zhong Hao
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Remanent Polarization ◽  
Perovskite Phase ◽  
Buffer Layers ◽  
Electrical Performance ◽  
Electrical Measurements ◽  
Sapphire Substrates ◽  
Low Leakage ◽  
Low Leakage Current

BiFeO3 (BFO) thin films were deposited by pulsed laser deposition (PLD) on c-plane sapphire substrates with a double SrTiO3/TiO2 oxide buffer layer grown by laser molecular beam epitaxy (laser-MBE). X-ray diffraction data showed the highly (111)-oriented perovskite phase in the BFO films with SrTiO3/TiO2 buffer layers, compared to the polycrystalline thin film grown directly on sapphire substrates. The epitaxial BiFeO3 thin films inherit its orientation from the underlying SrTiO3 buffer layer and have two in-plane orientations: (111)[1-10] BiFeO3 // (0001)[1-100] Al2O3 plus a twin variant related by a 180° in-plane rotation. The BiFeO3 thin films with the buffer layer show an out-of-plane remanent polarization of 81.5μC/cm2, which is comparable to the remanent polarization of BiFeO3 prepared on other single crystal substrates. Electrical measurements demonstrate that the BiFeO3 thin films with the buffer layer exhibit excellent fatigue endurance and a low leakage current density relative to the films without the buffer layer. These results indicate that the (111)-oriented BiFeO3 films with favorable electrical performance could be epitaxially grown on sapphire substrates using the double SrTiO3/TiO2 buffer layer.

Evaluation of (In,Ga)N Films as Optical Absorption Filters for Application in Integrated Fluorescence Detection Micro-Bioanalytical Systems

2001 ◽  
Vol 693 ◽  
Author(s):  
J. Alex Chediak ◽  
Michael Kneissl ◽  
Timothy D. Sands
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Fluorescence Detection ◽  
Green Light ◽  
Optical Filters ◽  
Buffer Layers ◽  
Fluorescence Signal ◽  
Sigmoidal Function ◽  
Sapphire Substrates ◽  
Pl Intensity

AbstractFluorescence detection in integrated micro-bioanalytical systems requires the selective exclusion of light from the excitation source (typically blue or UV) and transmission of the longer wavelength fluorescence signal. In the present research, the application of (In,Ga)N alloy thin films as optical filters for absorption of blue (470 nm) and transmission of green (530 nm) has been evaluated. Absorption spectra, photoluminescence (PL) and Rutherford backscattering spectroscopy (RBS) results are presented for 200-400 nm (In,Ga)N thin films grown by MOCVD on sapphire substrates with 2-4 μm GaN buffer layers. A sigmoidal function was used to model the absorption coefficient of (In,Ga)N as a function of energy, Eg, and the broadening (ΔE) associated with the Urbach tail. Experimental data showed that, as expected, the absorption band edge for (In,Ga)N films broadened with increasing InN mole%. An increase in ΔE of 35 meV was observed when the InN mole% was increased from 10 to 16%. The sigmoidal function model provided a good fit to the experimental data, which allowed the experimental data to be extrapolated to higher InN concentrations. Based on this analysis, it is predicted that a 5 μm thick In0.22Ga0.78N film should transmit 50% of green light (530 nm) and only 3.29 x 1 0-4 of blue light (470 nm). The (In,Ga)N films that have been evaluated range in InN mole% from ~2-16%. The higher InN mole% samples (10-16%) can successfully filter lower wavelengths (e.g., 400 nm). For a filter application, it is also important that photoluminescence be effectively suppressed. In MQW structures, high PL intensity is often obtained by means of InN segregation (InN-rich nanoclusters). But for our evaluation with 200-400 nm (In,Ga)N films, relaxation of coherency strain results in large densities of dislocations, and correspondingly low PL intensity.

Large Area Pulsed Laser Deposition of YBCO Thin Films and Buffer Layers on 3-Inch Wafers

1994 ◽  
Vol 341 ◽  
Author(s):  
M. Lorenz ◽  
H. Hochmuth ◽  
H. Börner ◽  
D. Natusch ◽  
K. Kreher
Keyword(s):  
Thin Films ◽  
Buffer Layer ◽  
Thickness Distribution ◽  
Buffer Layers ◽  
Large Area ◽  
Promising Technique ◽  
Laser Plume ◽  
Ybco Thin Films ◽  
Epitaxial Oxide

AbstractAn arrangement for large area PLD on 3-inch wafers is proposed. In order to get a homogeneous stoichiometry and thickness distribution and small variations of superconducting properties on the 3-inch diameter, the substrate is foreseen to be rotated and additionally laterally moved up to 45 mm during deposition whereas the laser plume remains fixed.YSZ buffer layers showed thickness homogeneity of 1% within 10 mm, of 4% within 2 inch and of 8% within 3 inch diameter, respectively. For in-situ deposited YBCO thin films on r-plane sapphire with YSZ buffer layer we inductively measured within 3 inch diameter values of the critical temperature Tc(90%) from 85.9 K to 86.7 K and values of the critical current density jc(77 K) from 1 × 106 to 2 × 106 A/cm2. However, up to now the degree of epitaxy of the YBCO thin films on r-plane sapphire with YSZ buffer layer is lower compared to YBCO on MgO(100) as determined by Raman spectroscopy. Nevertheless, large area PLD seems to be a very promising technique for homogeneous coating of 3-inch wafers by epitaxial oxide thin films.

Epitaxial Growth of Cerium Oxide Buffer Layers on MgO, YSZ and Sapphire Substrates

2000 ◽  
Vol 619 ◽  
Author(s):  
A. Thorley ◽  
S. Gnanarajan ◽  
A. Katsaros ◽  
N. Savvides
Keyword(s):  
Thin Films ◽  
Epitaxial Growth ◽  
Buffer Layers ◽  
Metal Target ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
X Ray ◽  
Sapphire Substrates ◽  
Pole Figures ◽  
Biaxial Alignment

ABSTRACTWe studied the epitaxial growth of CeO2 thin films deposited onto MgO(100), YSZ(100) and Al2O3(1102 ) (r-plane sapphire) substrates by reactive dc magnetron sputtering of a Ce metal target in an Ar/O2 plasma. The crystalline quality and biaxial alignment of the films was determined using x-ray diffraction techniques (θ-2θ, ω-scans, pole figures, ø-scans). The CeO2/MgO(100) and CeO2/Al2O3(1102) epitaxy was evident at 600°C and developed to nearly perfect biaxial alignment at 850°C with Δø = 5° and 9° respectively. The CeO2/YSZ (100) epitaxy occurred below 300°C while deposition at ≥ 650°C led to single-crystal quality CeO2 films with Δø = 0.2°.

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