Microstructure and Kinetics of the Interface Reaction Between Titanium Thin Films and (112) Sapphire Substrates

1989 ◽  
Vol 167 ◽  
Author(s):  
J.H. Selverian ◽  
F.S. Ohuchi ◽  
M.R. Notis
Keyword(s):  
Cross Section ◽  
Interface Reaction ◽  
Interfacial Region ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Titanium Thin Films ◽  
Thickness Measurements ◽  
Kinetics Of

AbstractWe studied the reactivity of titanium with the R-plane (112) surface of sapphire by transmission electron microscopy (TEM), x-ray diffraction (XRD), and Rutherford backscattering (RBS) techniques. Cross-section TEM specimens were prepared from 200–400 nm thick titanium films deposited on sapphire at 25, 525, 554, 562, 580, 630, and 663°C to observe the interfacial region. In samples deposited at 25°C, without further annealing, no reaction zone could be seen in the TEM. In all other samples titanium reduced the sapphire to form Ti0 6 7[O0 3 3] and Ti3Al[O], Ti and Ti3Al with oxygen in solid solution. An activation energy of 24.7 ± 6 kcal/deg-mole was determined for the growth of the Ti3Al[O] layer. Layer thickness measurements from the TEM and RBS studies were within 10–20% of one another.

The kinetics of indium/amorphous-selenium multilayer thin film reactions

1999 ◽  
Vol 14 (3) ◽  
pp. 771-779 ◽  
Author(s):  
K. Lu ◽  
M. L. Sui ◽  
J. H. Perepezko ◽  
B. Lanning
Keyword(s):  
Interface Reaction ◽  
Amorphous Selenium ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Transmission Electron ◽  
Dimensional Growth ◽  
Kinetics Of ◽  
Modulation Wavelength

The reaction kinetics in vapor-deposited indium/amorphous-selenium (a-Se) multilayer thin films were studied using differential scanning calorimetry (DSC), x-ray diffraction (XRD), and transmission electron microscopy (TEM). A number of reactions were observed upon heating with characteristic temperatures which were found to be independent of the multilayer modulation wavelength. The initial interface reaction between In and a-Se is the formation of an In2Se phase. Kinetic analyses of the In2Se formation process combined with TEM observations indicated that interface reaction is characterized by the two-dimensional growth of pre-existing In2Se regions formed during deposition to impingement in the plane of the original In/a-Se interface. The change of the density of In2Se grains with temperature was analyzed in terms of the derived kinetic parameters, which is consistent with TEM observations and the heat release measurements.

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.

AlxGa1-xN-Based Materials and Heterostructures

1996 ◽  
Vol 449 ◽  
Author(s):  
P. Kung ◽  
A. Saxler ◽  
D. Walker ◽  
X. Zhang ◽  
R. Lavado ◽  
...  
Keyword(s):  
Chemical Vapor ◽  
Bragg Reflectors ◽  
X Ray Diffraction ◽  
Chemical Vapor Deposition Growth ◽  
X Ray ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Dimensional Electron Gas ◽  
P Type

ABSTRACTWe present the metalorganic chemical vapor deposition growth, n-type and p-type doping and characterization of AlxGa1-xN alloys on sapphire substrates. We report the fabrication of Bragg reflectors and the demonstration of two dimensional electron gas structures using AlxGa1-xN high quality films. We report the structural characterization of the AlxGa1-xN / GaN multilayer structures and superlattices through X-ray diffraction and transmission electron microscopy. A density of screw and mixed threading dislocations as low as 107 cm-2 was estimated in AlxGa1-xN / GaN structures. The realization of AlxGa1-xN based UV photodetectors with tailored cut-off wavelengths from 365 to 200 nm are presented.

InAs Quantum Dots Grown on an AlGaAsSb Strain-Relief Buffer

2000 ◽  
Vol 642 ◽  
Author(s):  
A.L. Gray ◽  
L. R. Dawson ◽  
Y. Lin ◽  
A. Stintz ◽  
Y.-C. Xin ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Cross Section ◽  
Gaas Substrate ◽  
Buffer Layers ◽  
Threading Dislocations ◽  
X Ray Diffraction ◽  
Strain Relief ◽  
Inas Quantum Dots ◽  
X Ray ◽  
Transmission Electron

ABSTRACTAn In(Ga)As-based self-assembled quantum dot laser test structure grown on strain-relief Al0.5Ga0.5As1-ySby strain-relief buffer layers (0≤y ≤ 0.24) on a GaAs substrate is investigated in an effort to increase dot size and therefore extend the emission wavelength over conventional InAs quantum dots on GaAs platforms. Cross-section transmission electron microscopy, and high-resolution x-ray diffraction are used to monitor the dislocation filtering process and morphology in the buffer layers. Results show that the buffer layers act as an efficient dislocation filter by drastically reducing threading dislocations, thus providing a relaxed, low dislocation, compositionally modulated Al0.5Ga0.5Sb0.24As0.76 substrate for large (500Å height x 300Å width) defect -free InAs quantum dots. Photoluminescence shows a ground-state emission of the InAs quantum dots at 1.45 μm.

Transformation kinetics for mullite in kaolin–Al2O3 ceramics

2003 ◽  
Vol 18 (6) ◽  
pp. 1355-1362 ◽  
Author(s):  
Yung-Feng Chen ◽  
Moo-Chin Wang ◽  
Min-Hsiung Hon
Keyword(s):  
Glassy Phase ◽  
Avrami Equation ◽  
Mullite Formation ◽  
Transformation Kinetics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Energy Dispersion Spectrometry ◽  
Two Stages ◽  
Kinetics Of

Transformation kinetics of mullite formation in kaolin–Al2O3 ceramics was studied by x-ray diffraction, transmission electron microscopy, and energy dispersion spectrometry. The mullitization process of kaolin–Al2O3 ceramics is described by two stages; one is the primary mullite transformation at 1273 to 1573 K, and the other is the secondary mullite formation at 1573 to 1873 K. The activation energy of 1164.6 kJ mol-1 obtained for the secondary mullite formation is lower than 1356.9 kJ mol-1 for the primary mullite transformation by the general form of the Johnson–Mehl–Avrami equation. The lower value of growth morphology parameter strongly supports that in the secondary mullite formation the added alumina is dissolved into glassy phase and the mullite is then precipitated.

Characterization of Nanocrystalline γ–Fe2O3Prepared by Wet Chemical Method

1999 ◽  
Vol 14 (4) ◽  
pp. 1570-1575 ◽  
Author(s):  
G. Ennas ◽  
G. Marongiu ◽  
A. Musinu ◽  
A. Falqui ◽  
P. Ballirano ◽  
...  
Keyword(s):  
Isothermal Treatment ◽  
X Ray Diffraction ◽  
Ferrous Chloride ◽  
Scanning Calorimetry ◽  
Direct Transformation ◽  
X Ray ◽  
Transmission Electron ◽  
Xrd Techniques ◽  
Kinetics Of

Homogeneous maghemite (γ–Fe2O3) nanoparticles with an average crystal size around 5 nm were synthesized by successive hydrolysis, oxidation, and dehydration of tetrapyridino-ferrous chloride. Morphological, thermal, and structural properties were investigated by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and x-ray diffraction (XRD) techniques. Rietveld refinement indicated a cubic cell. The superstructure reflections, related to the ordering of cation lattice vacancies, were not detected in the diffraction pattern. Kinetics of the solid-state phase transition of nanocrystalline maghemite to hematite (α–Fe2O3), investigated by energy dispersive x-ray diffraction (EDXRD), indicates that direct transformation from nanocrystalline maghemite to microcrystalline hematite takes place during isothermal treatment at 385 °C. This temperature is lower than that observed both for microcrystalline maghemite and for nanocrystalline maghemite supported on silica.

Crystallization kinetics of yttrium aluminum garnet (Y3Al5O12)

2001 ◽  
Vol 16 (6) ◽  
pp. 1795-1805 ◽  
Author(s):  
Bradley R. Johnson ◽  
Waltraud M. Kriven
Keyword(s):  
Yttrium Aluminum Garnet ◽  
Three Dimensional ◽  
Constant Number ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Yttrium Aluminum ◽  
Temperature Transformation ◽  
Kinetics Of ◽  
Dimensional Crystal

The kinetics and pathways for crystallization of solid, amorphous, yttrium aluminum garnet (YAG) were studied using isothermal differential thermal analysis, x-ray diffraction, and transmission electron microscopy. The activation energy for crystallization was 437 KJ/mol and the measured Avrami exponent was 2.74, which corresponded to three-dimensional crystal growth with a constant number of nuclei. Time–temperature–transformation (T–T–T) curves were developed from the data to predict crystallization rates as a function of temperature. The crystallization pathway for YAG in this system is compared to others reported in the literature.

Growth and Characterization of (012)- and (001)-Oriented Epitaxial Anatase Thin Films

2006 ◽  
Vol 46 ◽  
pp. 146-151
Author(s):  
Andriy Lotnyk ◽  
Stephan Senz ◽  
Dietrich Hesse
Keyword(s):  
Thin Films ◽  
Cross Section ◽  
Single Phase ◽  
Electron Beam Evaporation ◽  
X Ray Diffraction ◽  
Tio2 Thin Films ◽  
X Ray ◽  
Transmission Electron

Single phase TiO2 thin films of anatase structure have been prepared by reactive electron beam evaporation. Epitaxial (012)- and (001)-oriented anatase films were successfully obtained on (110)- and (100)-oriented SrTiO3 substrates, respectively. X-ray diffraction and cross section transmission electron microscopy investigations revealed a good epitaxial quality of the anatase films grown on the SrTiO3 substrates.

Interdiffusion Kinetics and Magnetic Properties of TA-Permalloy Multilayers

1991 ◽  
Vol 232 ◽  
Author(s):  
I. Hashim ◽  
H. A. Atwater ◽  
K. T. Y. Kung ◽  
R. M. Valletta
Keyword(s):  
Magnetic Properties ◽  
Isothermal Annealing ◽  
Lattice Diffusion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Short Period ◽  
Interface Roughening ◽  
Interdiffusion Kinetics ◽  
Kinetics Of

ABSTRACTThe interdiffusion kinetics of ultrahigh vacuum deposited Ta/Ni81Fe19 short-period multilayers films have been investigated, and changes in microstructure were related to magnetic properties. Small angle X-ray diffraction and transmission electron microscopy were used to study layer morphology evolution and interdiffusion during post-growth isothermal annealing in the temperature range 300 – 600°C. The kinetic analysis suggests that interface roughening due to grain growth, and grain-boundary mediated diffusion of Ta occurs concurrently at early anneal times in the Ni81Fe19 films. Subsequent grainboundary and lattice diffusion of Ta lead to a reduction of magnetization and increase in coercivity of Ni81Fe19.

Sign in / Sign up

Export Citation Format

Share Document