Alloying of Co ultrathin films on Pt(111) with Ag buffer layers

2000 ◽  
Vol 88 (2) ◽  
pp. 705-709 ◽  
Author(s):  
C. S. Shern ◽  
C. W. Su ◽  
Y. E. Wu ◽  
T. Y. Fu
Keyword(s):  
Ultrathin Films ◽  
Buffer Layers

Alloy formation of Ni ultrathin films on Pt(1 1 1) with Ag buffer layers

2004 ◽  
Vol 237 (1-4) ◽  
pp. 306-310 ◽  
Author(s):  
H.Y. Ho ◽  
C.W. Su ◽  
Y.W. Chu ◽  
C.S. Shern
Keyword(s):  
Ultrathin Films ◽  
Buffer Layers ◽  
Alloy Formation

The measurement of thin-film reaction layers with high-resolution FESEM

1995 ◽  
Vol 53 ◽  
pp. 330-331
Author(s):  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Reaction Layer ◽  
Product Layer ◽  
Buffer Layers ◽  
Oxide Superconductors ◽  
Rate Limiting Step ◽  
Ceramic Thin Film ◽  
Backscattered Electron ◽  
Boundary Reaction

Thin-film reactions in ceramic systems are of increasing importance as materials such as oxide superconductors and ferroelectrics are applied in thin-film form. In fact, reactions have been found to occur during the growth of YBa2Cu3O6+x on ZrO2. Additionally, thin-film reactions have also been intentionally initiated for the production of buffer layers for the subsequent growth of high-Tc superconductor thin films. The problem is that the kinetics of ceramic thin-film reactions are not well understood when the reaction layer is very thin; that is, when the rate-limiting step is a phase-boundary reaction as opposed to diffusion of the reactants through the product layer. In this case, the reaction layer is likely to be laterally non-uniform. In the present study, the measurement of thin reaction-product layers is accomplished by first digitally acquiring backscattered-electron images in a high-resolution field-emission scanning electron microscope (FESEM) followed by image analysis. Furthermore, the problem of measuring such small thicknesses (e.g., 20-500nm) over lengths of interfaces longer than 3mm is addressed.

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

{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).

In-Situ Study of NiO Growth on Textured Nickel Tape Using Environmental Scanning Electron Microscope (ESEM) and Hot Stage

2001 ◽  
Vol 7 (S2) ◽  
pp. 1276-1277
Author(s):  
Y. Akin ◽  
R.E. Goddard ◽  
W. Sigmund ◽  
Y.S. Hascicek
Keyword(s):  
Buffer Layer ◽  
Lattice Mismatch ◽  
Sol Gel ◽  
Surface Oxidation ◽  
Dip Coating ◽  
Buffer Layers ◽  
Superconducting Film ◽  
Environmental Scanning ◽  
Cold Rolling And Annealing

Deposition of highly textured ReBa2Cu3O7−δ (RBCO) films on metallic substrates requires a buffer layer to prevent chemical reactions, reduce lattice mismatch between metallic substrate and superconducting film layer, and to prevent diffusion of metal atoms into the superconductor film. Nickel tapes are bi-axially textured by cold rolling and annealing at appropriate temperature (RABiTS) for epitaxial growth of YBa2Cu3O7−δ (YBCO) films. As buffer layers, several oxide thin films and then YBCO were coated on bi-axially textured nickel tapes by dip coating sol-gel process. Biaxially oriented NiO on the cube-textured nickel tape by a process named Surface-Oxidation- Epitaxy (SEO) has been introduced as an alternative buffer layer. in this work we have studied in situ growth of nickel oxide by ESEM and hot stage.Representative cold rolled nickel tape (99.999%) was annealed in an electric furnace under 4% hydrogen-96% argon gas mixture at 1050°C to get bi-axially textured nickel tape.

Exciton dynamics in thick GaN MOVPE epilayers deposited on sapphire.

1997 ◽  
Vol 2 ◽  
Author(s):  
J. Allègre ◽  
P. Lefebvre ◽  
J. Camassel ◽  
B. Beaumont ◽  
Pierre Gibart
Keyword(s):  
Layer Thickness ◽  
Buffer Layers ◽  
Rate Equations ◽  
Time Resolved ◽  
Versus Layer ◽  
Level Model ◽  
Shallow Impurities ◽  
Aln Buffer ◽  
Time Resolved Photoluminescence

Time-resolved photoluminescence spectra have been recorded on three GaN epitaxial layers of thickness 2.5 μm, 7 μm and 16 μm, at various temperatures ranging from 8K to 300K. The layers were deposited by MOVPE on (0001) sapphire substrates with standard AlN buffer layers. To achieve good homogeneities, the growth was in-situ monitored by laser reflectometry. All GaN layers showed sharp excitonic peaks in cw PL and three excitonic contributions were seen by reflectivity. The recombination dynamics of excitons depends strongly upon the layer thickness. For the thinnest layer, exponential decays with τ ~ 35 ps have been measured for both XA and XB free excitons. For the thickest layer, the decay becomes biexponential with τ1 ~ 80 ps and τ2 ~ 250 ps. These values are preserved up to room temperature. By solving coupled rate equations in a four-level model, this evolution is interpreted in terms of the reduction of density of both shallow impurities and deep traps, versus layer thickness, roughly following a L−1 law.

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