Thermodynamic Stability of Ptal Thin Films on GaAs

1990 ◽  
Vol 181 ◽  
Author(s):  
Dae-Hong Ko ◽  
Robert Sinclair
Keyword(s):  
Thin Films ◽  
Solid Phase ◽  
Second Stage ◽  
Sequential Deposition ◽  
Low Temperature Annealing ◽  
Gaas Substrates ◽  
Transmission Electron ◽  
C 30 ◽  
Two Stages ◽  
Thermal Stability Of

ABSTRACTThe thermal stability of PtAl thin films on GaAs substrates has been studied using transmission electron microscopy and Auger electron spectroscopy. The PtAl thin films were formed by sequential deposition of discrete Pt and Al layers on GaAs by e-beam evaporation followed by subsequent annealing processes. Interfacial reactions in the Al/Pt/GaAs system proceed in two stages. Upon low temperature annealing Pt and GaAs react to form PtGa and PtAs2. Further high temperature annealing causes PtGa, PtAs2 and Al to react together producing the desired PtAl on GaAs. We observed solid-phase epitaxial regrowth of GaAs during the second stage of reaction. The PtAl/GaAs interface is determined to be thermally stable during an 800°C/30 min. anneal, while remaining morphologically uniform on GaAs.

scholarly journals Nickel(III) containing layered double hydroxides with hydrotalcite structure

2019 ◽  
Vol 57 (2) ◽  
pp. 116-122
Author(s):  
Irina G. Ryltsova ◽  
◽  
Olga V. Nestroinaia ◽  
Olga E. Lebedeva ◽  
◽  
...  
Keyword(s):  
Heat Treatment ◽  
Layered Double Hydroxides ◽  
Reaction System ◽  
Second Stage ◽  
Transmission Electron ◽  
Crystalline Water ◽  
Two Stages ◽  
Double Hydroxides ◽  
Synthesized Materials ◽  
Thermal Stability Of

Synthesis of layered double hydroxides (LDH) was carried out by the method of coprecipitating of components from the solution at room temperature and variable pH, followed by aging at 98 °C for 2 days. During the synthesis the following compositions were specified: M2+6M3+1.5Ni3+0.5, where M2+ is Mg, Cu or Ca, M3+ is Al, Fe, or Co. In order to convert nickel cations to oxidation state +3, an oxidizing agent – sodium hypochlorite – was introduced into the reaction system. It is shown that the use of this method of synthesis allows to obtain layered double hydroxides containing aluminum and nickel or iron and nickel in the positions of triply charged cations in the structure of brucite-like layers. The formation of hydrotalcite-like structure was confirmed by XRD. The synthesized materials had morphology typical for layered double hydroxides. According to transmission electron microscopy, the samples consisted of aggregates of plate-like particles. The behavior during heat treatment was studied by thermogravimetric analysis. It was shown that the replacement of aluminum with iron cations in the structure of nickel-containing LDH led to a slight decrease in thermal stability of LDH. The thermal destruction of the obtained samples occured in two stages. The first stage, observed in the temperature range from 20 to 220 °C, included the loss of physically sorbed and crystalline water. In the second stage, when heated above 220 °C, simultaneous dehydroxylation of brucite-like layers and removal of carbonate anions from the interlayer space were observed, which resulted in the destruction of the layered structure. Heat treatment at 500 °C led to the transformation of layered double hydroxides into a mixture of corresponding oxides.

In-Situ Study of Ti/TiN Stability under Nitrogen Anneal

1999 ◽  
Vol 564 ◽  
Author(s):  
P. W. DeHaven ◽  
K. P. Rodbell ◽  
L. Gignac
Keyword(s):  
Annealing Temperature ◽  
Time Range ◽  
Second Phase ◽  
Transformation Rate ◽  
Transformation Mechanism ◽  
Second Stage ◽  
Transmission Electron ◽  
Reaction Proceeds ◽  
Two Stages

AbstractThe effectiveness of a TiN capping layer to prevent the conversion of α-titantium to titanium nitride when annealed in a nitrogen ambient has been studied over the temperature range 300–700°C using in-situ high temperature diffraction and transmission electron microscopy. Over the time range of interest (four hours), no evidence of Ti reaction was observed at 300°C. At 450°C. nitrogen was found to diffuse into the Ti to form a Ti(N) solid solution. Above 500°C the titanium is transformed to a second phase: however this reaction follows two different kinetic paths, depending on the annealing temperature. Below 600°C. the reaction proceeds in two stages, with the first stage consisting of Ti(N) formation, and the second stage consisting of the conversion of the Ti(N) with a transformation mechanism characteristic of short range diffusion (grain edge nucleation). Above 600°C, a simple linear transformation rate is observed.

Characterization of pulsed laser deposited MoS2 by transmission electron microscopy

1993 ◽  
Vol 8 (11) ◽  
pp. 2933-2941 ◽  
Author(s):  
S.D. Walek ◽  
M.S. Donley ◽  
J.S. Zabinski ◽  
V.J. Dyhouse
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Solid Phase ◽  
Analytical Electron Microscopy ◽  
Pulsed Laser ◽  
Cross Sectional ◽  
Aerospace Applications ◽  
Transmission Electron ◽  
Novel Method

Molybdenum disulfide is a technologically important solid phase lubricant for vacuum and aerospace applications. Pulsed laser deposition of MoS2 is a novel method for producing fully dense, stoichiometric thin films and is a promising technique for controlling the crystallographic orientation of the films. Transmission electron microscopy (TEM) of self-supporting thin films and cross-sectional TEM samples was used to study the crystallography and microstructure of pulsed laser deposited films of MoS2. Films deposited at room temperature were found to be amorphous. Films deposited at 300 °C were nanocrystalline and had the basal planes oriented predominately parallel to the substrate within the first 12–15 nm of the substrate with an abrupt upturn into a perpendicular (edge) orientation farther from the substrate. Spherically shaped particles incorporated in the films from the PLD process were found to be single crystalline, randomly oriented, and less than about 0.1 μm in diameter. A few of these particles, observed in cross section, had flattened bottoms, indicating that they were molten when they arrived at the surface of the growing film. Analytical electron microscopy (AEM) was used to study the chemistry of the films. The x-ray microanalysis results showed that the films have the stoichiometry of cleaved single crystal MoS2 standards.

The Red-Shift of Surface Plasmon Absorption of 2D Nanogold Arrangement from Disordered to Ordered

2008 ◽  
Vol 8 (1) ◽  
pp. 348-352 ◽  
Author(s):  
Junke Tang ◽  
Jinru Li ◽  
Huiling Rong ◽  
Bingsuo Zou ◽  
Long Jiang
Keyword(s):  
Long Range ◽  
Surface Plasmon ◽  
Red Shift ◽  
Strong Increase ◽  
Two Dimension ◽  
Second Stage ◽  
Transmission Electron ◽  
Dipolar Moment ◽  
Random Patterns ◽  
Two Stages

In this article, the changing of surface plasmon resonance (SPR) absorption of 2D arrangement of Au (3 nm) nanoparticles coated with 1-dodecanethiol (C12H25SH), obtained at different desolvation extents, had been investigated. It has been found that an obvious red-shifted happened when these arrays changed from loose, disordered to close-packed and ordered. Both transmission electron microscopy pictures and variation of SPR absorption of these arrays showed that the formation of long range two-dimension (2D) arrangement of nanoparticles coated with C12H25SH might be involved in two stages: At the first stage the particles can move freely and random patterns from loose to close package was driven by the Brownian Movement of solvated particles and as a result the voids were eliminated. The red shift of SPR absorption with the coverage (dλ/d) is relative low. At the second stage, where the particles cannot move freely because of lack of solvent and a long-range two-dimension crystal was formed, the SPR shift to a longer wavelength with a larger dλ/d. It is mainly attributed to the strong increase of the orientation and dipolar moment of the absorbed C12H25SH molecule on nanoparticles.

Thermal stability of coevaporated Al‐Pt thin films on GaAs substrates

1990 ◽  
Vol 57 (4) ◽  
pp. 392-394 ◽  
Author(s):  
B. Blanpain ◽  
G. D. Wilk ◽  
J. O. Olowolafe ◽  
J. W. Mayer ◽  
L. R. Zheng
Keyword(s):  
Thin Films ◽  
Thermal Stability ◽  
Gaas Substrates ◽  
Thermal Stability Of

Epitaxial Growth of Rare Earth Silicides on (111)Si

1993 ◽  
Vol 312 ◽  
Author(s):  
T. L. Lee ◽  
W. D. Sue ◽  
J. H. Lin ◽  
C. H. Luo ◽  
L. J. Chen
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Diffraction Pattern ◽  
Solid Phase ◽  
Stacking Faults ◽  
Metal Thin Films ◽  
Step Structure ◽  
Displacement Vectors ◽  
Transmission Electron ◽  
Long Time

AbstractEpitaxial YSi2-x, TbSi2-x, and ErSi2-x. have been grown on (111)Si by solid phase epitaxy in ultrahigh vacuum deposited rare earth (RE) metal thin films on silicon. The evolution of vacancy ordering and defect structure in epitaxial RE silicide thin films on (111)Si have been studied by both conventional and high resolution transmission electron microscopy.Additional superlattice spots located at 1/3 <2110> in the diffraction pattern of RESi2-x, are attributed to the formation of ordered vacancy in the Si sublattice planes. The splitting of extra diffraction spots is correlated to the formation of an out-of--step structure. Streakings of the split diffraction spots in the diffraction pattern are attributed to the presence of an out-of-step structure with a range of M values. For YSi2-x and ErSi2-x, the M was found to settle down to a constant value after high temperature and/or long time annealing. For TbSi2-x, M is equal to 5 throughout the annealing.Planar defects in RESi2-x films were analyzed to be stacking faults on {1010} planes with 1/6<1213> displacement vectors. The size and density of stacking faults were found to increase and decrease, respectively, with annealing temperature and/or annealing time.

Heteroepitaxial Bi2Sr2CaCu2Ox Superconducting thin films Deposited on LaA1O3 by Solid Phase Epitaxy and OMCVD

1992 ◽  
Vol 275 ◽  
Author(s):  
J. Chen ◽  
H. A. Lu ◽  
F. DiMeo ◽  
B. W. Wessels ◽  
D. L. Schulz ◽  
...  
Keyword(s):  
Thin Films ◽  
Solid Phase ◽  
Chemical Vapor ◽  
Superconducting Thin Films ◽  
Epitaxial Thin Films ◽  
Solid Phase Epitaxy ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Film Substrate

ABSTRACT-Heteroepitaxial superconducting Bi,Sr2CaCu2Ox (BSCCO 2212) thin films have been formed by solid phase epitaxy from amorphous films deposited on (100) LaA1O3 single crystal substrates by organometallic chemical vapor deposition. The epitaxial structure of the film is confirmed by x-ray diffraction including θ/2θ and Φ (in plane rotation) scans. Cross-sectional high resolution transmission electron microscopy indicates that the film-substrate interface is nearly atomically abrupt. Improvements in superconducting properties of the epitaxial thin films are noted in comparison to highly textured films deposited on MgO.

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