A Study of the MBE Growth of MGO on The FE(001) Surface

1994 ◽  
Vol 357 ◽  
Author(s):  
J.L. Vassent ◽  
M. Dynna ◽  
G. Patrat ◽  
B. Gilles ◽  
A. Marty
Keyword(s):  
Room Temperature ◽  
Lattice Parameter ◽  
Electron Beam Evaporation ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Mbe Growth ◽  
Plane Lattice ◽  
Pseudomorphic Growth ◽  
Bulk Parameter

AbstractThe deposition of MgO on the Fe(001) surface has been carried out using electron beam evaporation. MgO is observed to grow epitaxially with a 45° rotation between the Fe(001) and MgO(001) unit cell axes. Oscillations in the intensity of the RHEED specular beam are observed at room temperature showing that growth is two-dimensional. The relaxation of the in-plane lattice parameter during the growth at room temperature has been investigated in-situ by measuring the position of the RHEED streaks and ex-situ with GIXD experiments. Pseudomorphic growth is observed up to about five monolayers. Then the in-plane lattice parameter starts to evolve towards the MgO bulk parameter. HREM shows that the relaxation of MgO occurs via the generation of 1/2<011> misfit dislocations which are non-uniformly spaced at the Fe/MgO interface.

In Situ Stress and Strain Measurements During the Growth of Cu/Ni (001) Multilayers

2000 ◽  
Vol 615 ◽  
Author(s):  
T. Bigault ◽  
F. Bocquet ◽  
S. Labat ◽  
O. Thomas ◽  
A. Marty ◽  
...  
Keyword(s):  
Room Temperature ◽  
Molecular Beam ◽  
Lattice Parameter ◽  
In Situ Stress ◽  
Stress And Strain ◽  
Strain Measurements ◽  
Curvature Measurements ◽  
Pseudomorphic Growth ◽  
Average Lattice

ABSTRACTCu/Ni (001) multilayers have been grown by molecular beam epitaxy at room temperature. In-situ electron diffraction and curvature measurements performed during the growth are presented. The average lattice parameter in the equiatomic multilayers evolves gradually towards the alloy lattice parameter. The in-plane lattice parameter of both Cu and Ni evolves continuously towards the bulk lattice parameter with no evidence of pseudomorphic growth. The combination of diffraction and curvature measurements suggests that the Ni on Cu interface is diffuse. This is attributed to the surfactant behaviour of Cu. This results shed new insights into the interesting magnetic properties of Ni films on Cu (001).

Real-Time Analysis Of In-Situ Spectroscopic Ellipsometric Data During Mbe Growth Of III-V Semiconductors

1991 ◽  
Vol 222 ◽  
Author(s):  
B. Johs ◽  
J. L. Edwards ◽  
K. T. Shiralagi ◽  
R. Droopad ◽  
K. Y. Choi ◽  
...  
Keyword(s):  
Real Time ◽  
Optical Constants ◽  
Growth Parameters ◽  
Ex Situ ◽  
Time Analysis ◽  
Mbe Growth ◽  
In Situ Data ◽  
Real Time Analysis

ABSTRACTA modular spectroscopic ellipsometer, capable of both in-situ and ex-situ operation, has been used to measure important growth parameters of GaAs/AIGaAs structures. The ex-situ measurements provided layer thicknesses and compositions of the grown structures. In-situ ellipsometric measurements allowed the determination of growth rates, layer thicknesses, and high temperature optical constants. By performing a regression analysis of the in-situ data in real-time, the thickness and composition of an AIGaAs layer were extracted during the MBE growth of the structure.

scholarly journals Ion-Irradiation-Induced Amorphization Of Cadmium Niobate Pyrochlore

2000 ◽  
Vol 650 ◽  
Author(s):  
A. Meldrum ◽  
K. Beaty ◽  
L. A. Boatner ◽  
C. W. White
Keyword(s):  
Electron Microscope ◽  
Ambient Temperature ◽  
Transmission Electron Microscope ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Ex Situ ◽  
Temperature Dependent ◽  
Transmission Electron ◽  
Ion Energies

ABSTRACTIrradiation-induced amorphization of Cd2Nb2O7 pyrochlore was investigated by means of in-situ temperature-dependent ion-irradiation experiments in a transmission electron microscope, combined with ex-situ ion-implantation (at ambient temperature) and RBS/channeling analysis. The in-situ experiments were performed using Ne or Xe ions with energies of 280 and 1200 keV, respectively. For the bulk implantation experiments, the incident ion energies were 70 keV (Ne+) and 320 keV (Xe2+). The critical amorphization temperature for Cd2Nb2O7 is ∼480 K (280 keV Ne+) or ∼620 K (1200 keV Xe2+). The dose for in-situ amorphization at room temperature is 0.22 dpa for Xe2+, but is 0.65 dpa for Ne+ irradiation. Both types of experiments suggest a cascade overlap mechanism of amorphization. The results were analyzed in light of available models for the crystalline-to-amorphous transformation and were compared to previous ionirradiation experiments on other pyrochlore compositions.

Microwave Phase Shifters: Epitaxial Growth by Pulsed Laser Deposition of Dielectric Ba0.5Sr0.5TiO3 Thin Films on MgO

2005 ◽  
Vol 902 ◽  
Author(s):  
YauYau Tse ◽  
P. S. Suherman ◽  
T. J. Jackson ◽  
I. P. Jones
Keyword(s):  
Thin Films ◽  
Pulsed Laser Deposition ◽  
Strain Relaxation ◽  
Pulsed Laser ◽  
Phase Shifters ◽  
Laser Deposition ◽  
Ex Situ ◽  
Misfit Dislocations ◽  
Epitaxial Relationship

AbstractBa0.5Sr0.5TiO3 (BSTO) thin films were grown on (001) MgO using pulsed-laser deposition (PLD). The microstructures of in-situ and ex-situ annealed BSTO films were studied by X-ray diffraction and transmission electron microscopy (TEM). The films showed a cube on cube epitaxial relationship with <100> BSTO // <100> MgO. They were essentially single crystals with a columnar structure and possessed smooth surfaces. The interfaces of the BSTO films and substrates were atomically sharp, with misfit dislocations. Better crystallinity and full strain relaxation was obtained in films grown in 10-1 mbar oxygen and annealed ex-situ. A 30% increase in dielectric tuneability was achieved compared with in-situ annealing and deposition at 10-4 mbar. Threading dislocations are the dominant defects in the films grown in 10-1 mbar oxygen and annealed ex-situ, while the films with in-situ annealing show columnar structures with low angle boundaries.

scholarly journals In situ oxidation kinetics of magnetite nanoparticles by total scattering

2014 ◽  
Vol 70 (a1) ◽  
pp. C736-C736
Author(s):  
Antonio Cervellino ◽  
Ruggero Frison ◽  
Antonella Guagliardi ◽  
Giuseppe Cernuto ◽  
Norberto Masciocchi ◽  
...  
Keyword(s):  
Materials Science ◽  
Particle Diameter ◽  
Indirect Evidence ◽  
Lattice Parameter ◽  
Oxidation States ◽  
Ex Situ ◽  
Total Scattering ◽  
X Ray ◽  
Specific Subset

Iron oxide nanoparticles (NPs) show different structures as a function of oxidation state. In particular, magnetite (Fe3O4) NPs are easily oxidized in air at moderate temperatures, eventually yielding maghemite (Fe2O3). Oxidation proceeds via the creation of iron vacancies. While the vacancies may be created with a random distribution throughout the octahedral Fe sites, they eventually order over a specific subset of these sites, lowering the symmetry from F-centered (magnetite) to P-centered (cubic maghemite). By ex situ X-ray Total Scattering studies of magnetite-maghemite NPs in different oxidation states[1] we have recently studied, by the DFA method[2], the correlation between particle diameter, stoichiometry and lattice parameter in polydisperse NP samples unraveling also the size dependence of lattice parameter and composition. Moreover, we have shown indirect evidence of the formation of a polycrystalline surface layer of maghemite on a magnetite core in the intermediate oxidation states. Motivated by the excellent ex-situ results, we have also performed in-situ studies where magnetite NPs were oxidised in air at moderate temperatures (50-200 C). We present here an in-situ study performed at the X04SA-Materials Science beamline of the Swiss Light Source synchrotron[3]. Total Scattering X-ray diffraction patterns were collected every few minutes, while the oxidation was completed within several hours. The mechanism of NPs oxidation - whereas a surface oxidised layer is formed by outwards diffusion of Fe, then the vacancies so created order themselves giving rise to the maghemite-magnetite phase transition, will be examined in great detail. We will discuss, on robust statistical basis, the calculation of kinetic and diffusion constants, the temperature effect on the lattice constant and on the thickness of the surface oxidised layer; the different possible structural models for the cubic-maghemite NPs. We thank for support Fondazione Cariplo (2009-0289).

Phase Transformations in Sol-Gel PZT Thin Films

2000 ◽  
Vol 623 ◽  
Author(s):  
D.P. Eakin ◽  
M.G. Norton ◽  
D.F. Bahr
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Structural Changes ◽  
Sol Gel ◽  
Ex Situ ◽  
Ambient Conditions ◽  
Crystalline Films ◽  
In Situ Heating

AbstractThin films of PZT were deposited onto platinized and bare single crystal NaCl using spin coating and sol-gel precursors. These films were then analyzed using in situ heating in a transmission electron microscope. The results of in situ heating are compared with those of an ex situ heat treatment in a standard furnace, mimicking the heat treatment given to entire wafers of these materials for use in MEMS and ferroelectric applications. Films are shown to transform from amorphous to nanocrystalline over the course of days when held at room temperature. While chemical variations are found between films crystallized in ambient conditions and films crystallized in the vacuum conditions of the microscope, the resulting crystal structures appear to be insensitive to these differences. Significant changes in crystal structure are found at 500°C, primarily the change from largely amorphous to the beginnings of clearly crystalline films. Crystallization does occur over the course of weeks at room temperature in these films. Structural changes are more modest in these films when heated in the TEM then those observed on actual wafers. The presence of Pt significantly influences both the resulting structure and morphology in both in situ and ex situ heated films. Without Pt present, the films appear to form small, 10 nm grains consisting of both cubic and tetragonal phases, whereas in the case of the Pt larger, 100 nm grains of a tetragonal phase are formed.

Ex situ and In situ TEM study of the relaxation of thin films by the modified frank-read mechanism

1992 ◽  
Vol 50 (2) ◽  
pp. 1342-1343
Author(s):  
F.K. LeGoues
Keyword(s):  
Thin Films ◽  
Strain Relaxation ◽  
Lattice Parameter ◽  
Buffer Layers ◽  
Ex Situ ◽  
In Situ Tem ◽  
Wide Range ◽  
Strong Resemblance ◽  
Image Position

In recent papers, we have described a novel mechanism for strain relaxation of thin films. Because of its strong resemblance to the well known Frank-Read sources of dislocations, it was called the “Modified-Frank-Read” (MFR) mechanism. This process was first observed during the growth of compositionally graded SiGe/Si(001) thin films, where it results in dislocations pile-ups being injected deep into an initially perfect substrate, leaving the topmost part of the film relaxed and nominally defect free. This last observation opens the door to a wide range of electronic applications since it makes it possible to grow electronic grade buffer layers of arbitrary composition and lattice parameter.The exact mechanism of the reproduction of dislocations was identified through tilting experiment and analysis of several compositionally graded SiGe/Si(001) structures. These also provided the important parameters controlling this mode of strain relaxation. We thus demonstrated that the MFR mechanism corresponds to the multiplication of “corner dislocations” (dislocations whose line forms a 90° angle) by simultaneous glide on two (111) planes.

Analysis of co-deposited Ti-Hf thin film on (0001)6H-SiC by HREM, energy-selected and hollow-cone images

1994 ◽  
Vol 52 ◽  
pp. 978-979
Author(s):  
J. S. Bow
Keyword(s):  
Thin Film ◽  
Solid Solution ◽  
Lattice Parameter ◽  
Dark Field ◽  
Electron Beam Evaporation ◽  
Structural Defects ◽  
Misfit Dislocations ◽  
Hollow Cone ◽  
Chemical Homogeneity ◽  
Dark Field Imaging

Solid solution binary alloys are attractive for defect-free thin film semiconductor contacts because lattice matching can be obtained by composition adjustment, but chemical homogeneity is required. Highly composition sensitive energy-selected and hollow cone (HC) dark field imaging were evaluated for heterogeneity detection in Ti-Hf films using an Ω filter/Zeiss 912 TEM. Conventional HREM, which relatively insensitive to spatial composition variations in this case, was used to observe structural defects in the films near the interfaces.Thin films of pure Ti deposited via UHV electron beam evaporation at room temperature on n-type, vicinal (0001) 6H-SiC showed good epitaxy. This contact displayed rectifying characteristics. The interface was both structurally and chemically sharp. However, misfit dislocations at “stand off” positions were found, due to 4 % mismatch between the basal parameters of Ti and SiC. same column with Ti in the periodic table and has hexagonal crystal structure, but larger lattice parameter (aHf = 3.196 Å, and aTi = 2.950 Å). The Ti-Hf solid solution system obeys Vergard's law well, that is, the lattice parameters of this alloy change linearly with composition.

Controlled Growth and Characterization of Non-tapered InN Nanowires on Si(111) Substrates by Molecular Beam Epitaxy

2009 ◽  
Vol 1178 ◽  
Author(s):  
Yi-Lu Chang ◽  
Arya Fatehi ◽  
Feng Li ◽  
Zetian Mi
Keyword(s):  
Molecular Beam Epitaxy ◽  
Epitaxial Growth ◽  
Room Temperature ◽  
Molecular Beam ◽  
Stacking Faults ◽  
Seeding Layer ◽  
Mbe Growth ◽  
Molecular Beam Epitaxial

AbstractWe have performed a detailed investigation of the molecular beam epitaxial (MBE) growth and characterization of InN nanowires spontaneously formed on Si(111) substrates under nitrogen rich conditions. Controlled epitaxial growth of InN nanowires (NWs) has been demonstrated by using an in situ deposited thin (˜ 0.5 nm) In seeding layer prior to the initiation of growth. By applying this technique, we have achieved non-tapered epitaxial InN NWs that are relatively free of dislocations and stacking faults. Such InN NW ensembles display strong photoluminescence (PL) at room temperature and considerably reduced spectral broadening, with very narrow spectral linewidths of 22 and 40 meV at 77 K and 300 K, respectively.

IN-SITU Analysis Of The Microstructure of Thermally Treated Thin Copper Films

1993 ◽  
Vol 309 ◽  
Author(s):  
J. Nucci ◽  
H. Neves ◽  
Y. Shacham ◽  
E. Eisenbraun ◽  
B. Zheng ◽  
...  
Keyword(s):  
Thin Films ◽  
Heat Treatment ◽  
Room Temperature ◽  
Thermal Evolution ◽  
Electron Beam Evaporation ◽  
Copper Films ◽  
Tem Analysis ◽  
Heat Treated ◽  
Baseline Information

AbstractCopper thin films were deposited by sputtering, electron beam evaporation, and electroless plating onto nitride membranes for TEM analysis. The samples were heat treated in-situ from room temperature to 600 °C for structural and chemical analysis. The as-deposited and heat treated microstructures were investigated. Orientation changes with heat treatment and reactions among the sample layers were analyzed by electron diffraction. This work provides baseline information for a study of the thermal evolution of copper lines.

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