Epitaxial Buffer Layers on (012) Sapphire and (100) SrTiO3 for the Integration of YBa2Cu3Ox in Microwave Devices and Squids

1992 ◽  
Vol 275 ◽  
Author(s):  
H. Schmidt ◽  
G. Vollnhals ◽  
G. Gieres ◽  
W. Wersing ◽  
H. Kinder
Keyword(s):  
Grain Boundaries ◽  
Epitaxial Growth ◽  
Pole Figure ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
X Ray ◽  
Layer Sequence ◽  
Ion Channeling ◽  
Sapphire Substrates ◽  
Microwave Applications

ABSTRACTThe epitaxial growth of YBa2Cu3Ox films on sapphire for microwave applications requires epitaxial buffer layers hindering interdiffusion. Therefore the epitaxial growth of YSZ, the layer sequence Y2O3/YSZ, and Y2O3 on (012) sapphire was examined. In addition the growth of MgO and srTiO3 on sapphire substrates and the growth of MgO and CeO2 on SrTiO3 substrates was studied by X-ray diffraction, X-ray pole figure measurement and RBS-ion channeling. With a combination of these buffer layers bi-epitaxial grain boundaries in YBa2Cu3Ox films can be fabricated in future.

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°.

Non-Polar GaN/AlN Superlattices on A-plane AlN (500nm) Buffer Layers Grown by RF-MBE

2004 ◽  
Vol 831 ◽  
Author(s):  
Takayuki Morita ◽  
Akihiko Kikuchi ◽  
Katsumi Kishino
Keyword(s):  
Molecular Beam ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Structural Quality ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Frequency Plasma ◽  
Diffraction Peaks ◽  
Rich Side

ABSTRACTThe growth conditions of A-plane AlN and GaN epitaxial layers by radio-frequency plasma assisted molecular beam epitaxy on R-plane sapphire substrates were investigated. The growth temperature and V/III supply ratio dependency on structural quality and surface roughness was described. The optimum V/III ratio for A-plane GaN and AlN layers was shifted to nitrogen rich side compared to the C-plane layers. A-plane GaN/AlN superlattices (SLs) were also grown on R-plane sapphire substrates. The X-ray diffraction peaks from a primary and a 1st satellite were observed. From a comparison of low temperature photoluminescence peak wavelength between A-plane and C-plane SLs, the built-in electrostatic field originated from spontaneous and piezoelectric polarization is negligible for A-plane SLs.

EPITAXIAL GROWTH OF BUFFER LAYERS AND YBCO FOR COATED CONDUCTOR

2007 ◽  
Vol 21 (18n19) ◽  
pp. 3156-3159
Author(s):  
J. YANG ◽  
H. Z. LIU ◽  
H. ZHANG ◽  
F. QU ◽  
Q. ZHOU ◽  
...  
Keyword(s):  
Magnetron Sputtering ◽  
Epitaxial Growth ◽  
Seed Layer ◽  
Yttria Stabilized Zirconia ◽  
Buffer Layers ◽  
Coated Conductor ◽  
Reactive Magnetron ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray

An Y 2 O 3 film, as seed layer, was directly deposited on the meter long length rolling assisted biaxially textured substrate (RABiTS) NiW tapes by the reactive magnetron sputtering process. Yttria stabilized zirconia (YSZ) and CeO 2 films were further carried out as the barrier and cap layers, and YBCO layer was prepared by magnetron sputtering technique as well. X-ray diffraction was employed to characterize the texture of film. The results showed that on NiW tapes highly textured films were obtained.

Pole Figure Analysis of Epitaxial Films of ZnO:2wt%Al Grown on Sapphire Substrates by RF Magnetron Sputtering

2002 ◽  
Vol 721 ◽  
Author(s):  
P. Kuppusami ◽  
S. Fiechter ◽  
K. Ellmer
Keyword(s):  
Magnetron Sputtering ◽  
Pole Figure ◽  
Room Temperature ◽  
Defect Density ◽  
Rf Magnetron Sputtering ◽  
Epitaxial Films ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Sapphire Substrates

AbstractAluminium-doped zinc oxide (ZnO:Al) films have been grown on c-plane (001) and a-plane (110) sapphire by RF magnetron sputtering from a ceramic target. The films grew epitaxially, even at room temperature. However, the crystalline quality depends both on the substrate temperature as well as on the sapphire orientation. The best films, proved by X-ray diffraction (rocking curves and pole figure measurements) were grown on (110)-oriented sapphire in the temperature range 473 to 773 K. The minimum rocking curve half width was about 0.75 °. By Rutherford backscattering analysis it could be shown, that the films exhibit a significant variation of the defect density over the film thickness. The highest density, as expected, is observed at the interface sapphire/ZnO:Al. Films grown on (001)-oriented sapphire have higher rocking curve half widths (about 1.3 °) and exhibit sometimes two types of domains in the same film twisted by 30 °.

On the Epitaxy of Metal Films on GaN

1996 ◽  
Vol 449 ◽  
Author(s):  
Q.Z. Liu ◽  
K.V. Smith ◽  
E.T. Yu ◽  
S.S. Lau ◽  
N.R. Perkins ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Mismatch ◽  
Metal Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Ion Channeling ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Determining Factor

ABSTRACTA variety of metal films deposited at room temperature have been found to grow epitaxially under conventional vacuum conditions on GaN grown by metalorganic vapor phase epitaxy on sapphire substrates. The metal films have been characterized by X-ray diffraction using a thin-film Read camera and by MeV ion channeling measurements. Lattice mismatch between the epitaxial metals and the GaN basal planes ranges from ∼ 0.2% to ∼ 22%, and does not appear to be the determining factor in the epitaxy reported here. Surface structure of the epitaxial metal films has been studied by atomic force microscopy and found to differ considerably from that of nonepitaxial metal films grown on similar GaN substrates.

Effect of Growth Conditions and Buffer Layers on the Metal-Insulator Transition in V2O3 Thin Films

1995 ◽  
Vol 401 ◽  
Author(s):  
H. Schuler ◽  
G. Weissmann ◽  
C. Renner ◽  
S. Six ◽  
S. Klimm ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Conditions ◽  
Buffer Layers ◽  
Infrared Transmission ◽  
X Ray Diffraction ◽  
Metal Insulator ◽  
X Ray ◽  
Sapphire Substrates ◽  
Hall Effect Measurements ◽  
Mi Transition

AbstractThin films of V2O3 with thickness from 20 to 450 nm were deposited on (0001) oriented sapphire substrates by reactive e-beam evaporation. LEED, x-ray diffraction and AFM studies show highly oriented grains with a lateral size of 50 to 800 nm, dependent on substrate temperature and deposition rate. The films were characterized by optical and infrared transmission, electrical resistance and Hall effect measurements. Films grown directly on the Al2O3-substrate show a very broad metal-insulator (MI) transition as a function of temperature. The width of the transition decreases with increasing film thickness. The insertion of Cr2O3 buffer layers decreases the transition width by a further factor of three. The electronic properties of the films can be drastically influenced by the growth conditions.

Ultra-Smooth ZnO Buffer Layers on (001) Sapphire

1997 ◽  
Vol 482 ◽  
Author(s):  
A. J. Drehman ◽  
S.-Q. Wang ◽  
P. W. Yip
Keyword(s):  
Buffer Layers ◽  
Zno Films ◽  
Potential Candidate ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Force Microscopy ◽  
Sapphire Substrates ◽  
Atomic Force ◽  
Electrical Resistivities

AbstractUsing off-axis reactive rf sputtering, we have grown extremely smooth, nearly epitaxial, (001) oriented ZnO films on c-axis sapphire substrates. Atomic Force Microscopy was used to determine that these films are extremely smooth, having an rms roughness of only a few tenths of a nanometer. Based on high resolution x-ray diffraction (HXRD), the ZnO is highly oriented, with a rocking curve width of less than 400 arc seconds for the (006) diffraction peak, and only somewhat larger for the (112) reflection. HXRD Phi scans show that the ZnO (112) reflection is rotated in the a-b plane by 30 degrees from the sapphire (113) direction. These two measurements indicate excellent in-plane orientation. We are investigating the use of these buffer layers for subsequent GaN growth. Electrical resistivities of the films exceeded 100 kΩ-cm making ZnO a potential candidate as an insulating buffer layer.

scholarly journals The impact of point defects in n-type GaN layers on thermal decomposition of InGaN/GaN QWs

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mikolaj Grabowski ◽  
Ewa Grzanka ◽  
Szymon Grzanka ◽  
Artur Lachowski ◽  
Julita Smalc-Koziorowska ◽  
...  
Keyword(s):  
Quantum Wells ◽  
High Temperatures ◽  
Point Defects ◽  
X Ray Diffraction ◽  
Helium Ions ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
The Impact ◽  
Ingan Quantum Wells

AbstractThe aim of this paper is to give an experimental evidence that point defects (most probably gallium vacancies) induce decomposition of InGaN quantum wells (QWs) at high temperatures. In the experiment performed, we implanted GaN:Si/sapphire substrates with helium ions in order to introduce a high density of point defects. Then, we grew InGaN QWs on such substrates at temperature of 730 °C, what caused elimination of most (but not all) of the implantation-induced point defects expanding the crystal lattice. The InGaN QWs were almost identical to those grown on unimplanted GaN substrates. In the next step of the experiment, we annealed samples grown on unimplanted and implanted GaN at temperatures of 900 °C, 920 °C and 940 °C for half an hour. The samples were examined using Photoluminescence, X-ray Diffraction and Transmission Electron Microscopy. We found out that the decomposition of InGaN QWs started at lower temperatures for the samples grown on the implanted GaN substrates what provides a strong experimental support that point defects play important role in InGaN decomposition at high temperatures.

Properties of Sputter Deposited ZnO Films Co-doped with Lithium and Phosphorus

2013 ◽  
Vol 1494 ◽  
pp. 77-82
Author(s):  
T. N. Oder ◽  
A. Smith ◽  
M. Freeman ◽  
M. McMaster ◽  
B. Cai ◽  
...  
Keyword(s):  
Rf Magnetron Sputtering ◽  
Zno Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Hall Effect Measurements ◽  
Sputter Deposited ◽  
P Type ◽  
Post Deposition ◽  
Co Doped

ABSTRACTThin films of ZnO co-doped with lithium and phosphorus were deposited on sapphire substrates by RF magnetron sputtering. The films were sequentially deposited from ultra pure ZnO and Li3PO4 solid targets. Post deposition annealing was carried using a rapid thermal processor in O2 and N2 at temperatures ranging from 500 °C to 1000 °C for 3 min. Analyses performed using low temperature photoluminescence spectroscopy measurements reveal luminescence peaks at 3.359, 3.306, 3.245 eV for the co-doped samples. The x-ray diffraction 2θ-scans for all the films showed a single peak at about 34.4° with full width at half maximum of about 0.17°. Hall Effect measurements revealed conductivities that change from p-type to n-type over time.

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