Rheed Studies of a-Axis Oriented DyBa2Cu3O7 Films Grown by All-MBE

1997 ◽  
Vol 502 ◽  
Author(s):  
Ivan Bozovic ◽  
J. N. Eckstein ◽  
Natasha Bozovic ◽  
J. O'Donnell
Keyword(s):  
Phase Transitions ◽  
Secondary Phase ◽  
Atomic Layer ◽  
High Energy ◽  
Layer By Layer ◽  
Growth Modes ◽  
Flow Surface ◽  
Surface Phase Transitions

ABSTRACTReal-time, in-situ surface monitoring by reflection high-energy electron diffraction (RHEED) has been the key enabling component of atomic-layer-by-layer molecular beam epitaxy (ALL-MBE) of complex oxides. RHEED patterns contain information on crystallographic arrangements and long range order on the surface; this can be made quantitative with help of numerical simulations. The dynamics of RHEED patterns and intensities reveal a variety of phenomena such as nucleation and dissolution of secondary-phase precipitates, switching between growth modes (layer-by-layer, step-flow), surface phase transitions (surface reconstruction, roughening, and even phase transitions induced by the electron beam itself), etc. Some of these phenomena are illustrated here, using as a case study our recent growth of atomically smooth a-axis oriented DyBa2Cu3O7 films.

Atomic Layer and Unit-Cell Layer Growth of (Ca,Sr)CuO2 and Bi2Sr2Can-1CunO2n+4 Thin Films by Laser Molecular Bean Epitaxy

1991 ◽  
Vol 222 ◽  
Author(s):  
Masaki Kanai ◽  
Tomoji Kawai ◽  
Takuya Matsumoto ◽  
Shichio Kawai
Keyword(s):  
Thin Films ◽  
Diffraction Pattern ◽  
Cell Layer ◽  
Atomic Layer ◽  
High Energy ◽  
Layer Growth ◽  
Unit Cell ◽  
Layer By Layer ◽  
Diffraction Intensity

ABSTRACTThin films of (Ca,Sr)CuO2 and Bi2Sr2Can-1CunO2n+4 are formed by laser molecular beam epitaxy with in-situ reflection high energy electron diffraction observation. The diffraction pattern shows that these materials are formed with layer-by-layer growth. The change of the diffraction intensity as well as the analysis of the total diffraction pattern makes It possible to control the grown of the atomic layer or the unit-cell layer.

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.

Surface phase transitions of adsorbed collector molecules as revealed by in situ FT-IR/IRS spectroscopy

1993 ◽  
Vol 10 (2) ◽  
pp. 75-80
Author(s):  
J. J. Kellar ◽  
W. M. Cross ◽  
M. R. Yalamanchili ◽  
C. A. Young ◽  
J. D. Miller
Keyword(s):  
Phase Transitions ◽  
Surface Phase ◽  
Surface Phase Transitions ◽  
Ft Ir

Atomic Layer Controlled Substitutional Doping With Lithium in ZnSe

1991 ◽  
Vol 222 ◽  
Author(s):  
Ziqiang Zhu ◽  
Mitsuo Kawashima ◽  
Takafumi Yao
Keyword(s):  
Adsorption Process ◽  
Intensity Variation ◽  
Atomic Layer ◽  
High Energy ◽  
Substitutional Doping ◽  
Dynamical Behaviors ◽  
Adsorption Processes ◽  
Li Adsorption ◽  
P Type

ABSTRACTThe detailed observation of dynamical behaviors of reflection high energy electron diffraction (RHEED) patterns during the adsorption processes of Li, Se and Zn is carried out. It is found that the RHEED intensity variation reflects the Li surface coverage during Li adsorption process on a Secovered surface. This fact enables one to control quantitatively the doping of Li “in situ”. A new method for atomic-layer controlled substitutional doping of ZnSe layers with lithium is proposed based on the RHEED investigations. The method allows the incorporation of Li dopants on Zn-sites of ZnSe by monitoring the RHEED patterns and intensities, and is expected to suppress the compensation by Li interstitials. Photoluminescence spectrum shows the growth of high quality p-type layers.

scholarly journals Phase transitions and in situ dynamics of crystal grain formation of alumina nanotubes templated by vertically aligned carbon nanotubes

RSC Advances ◽  
2015 ◽  
Vol 5 (83) ◽  
pp. 68251-68259 ◽  
Author(s):  
L. F. Lampert ◽  
A. Barnum ◽  
S. W. Smith ◽  
J. F. Conley ◽  
J. Jiao
Keyword(s):  
Carbon Nanotubes ◽  
Phase Transitions ◽  
Atomic Layer ◽  
Vertically Aligned Carbon Nanotubes ◽  
Layer Deposition ◽  
Aligned Carbon Nanotubes ◽  
Grain Formation ◽  
Vertically Aligned ◽  
Induced Crystallization

Vertically aligned alumina nanotubes created by atomic layer deposition onto carbon nanotubes scaffolds are synthesized and analyzed for phase transitionsviathermal annealing andin situelectron-irradiation induced crystallization.

Phase Transitions and Recrystallization in a Ti-46at%Al-9at%Nb Alloy as Observed by In-Situ High-Energy X-ray Diffraction

2006 ◽  
Vol 980 ◽  
Author(s):  
Klaus-Dieter Liss ◽  
Helmut Clemens ◽  
Arno Bartels ◽  
Andreas Stark ◽  
Thomas Buslaps
Keyword(s):  
Phase Transitions ◽  
Room Temperature ◽  
Strain Relaxation ◽  
Reciprocal Lattice ◽  
Lamellar Microstructure ◽  
High Energy ◽  
X Ray Diffraction ◽  
Orientation Relationships ◽  
X Ray

AbstractHigh-energy synchrotron X-ray diffraction is a powerful tool for bulk studies of materials. In this investigation, it is applied to the investigation of an intermetallic γ-TiAl based alloy with a composition of Ti-46Al-9Nb. The morphology of the reflections on the Debye-Scherrer rings is evaluated in order to approach grain sizes as well as crystallographic correlations. An in-situ heating cycle from room temperature to a temperature above the α-transus temperature has been conducted starting from a massively transformed sample. With increasing temperature the occurrence of strain relaxation, chemical and phase separation, domain orientations, phase transitions, recrystallization processes, and subsequent grain growth can be observed. During cooling to room temperature, crystallographic correlations between the re-appearing γ-phase and the host α-phase, known as the Blackburn correlation, are observed in the reciprocal lattice, which splits into different twinning and domain orientation relationships present in the fully lamellar microstructure.

In Situ Spectroscopic Approach to Atomic Layer Deposition

2002 ◽  
Vol 745 ◽  
Author(s):  
Martin M. Frank ◽  
Yves J. Chabal ◽  
Glen D. Wilk
Keyword(s):  
Infrared Spectroscopy ◽  
Atomic Layer Deposition ◽  
Aluminum Oxide ◽  
Atomic Layer ◽  
Gate Oxide ◽  
Silicon Surfaces ◽  
Oxide Growth ◽  
Layer By Layer ◽  
Layer Deposition

ABSTRACTThere is great need for a mechanistic understanding of growth chemistry during atomic layer deposition (ALD) of films for electronic applications. Since commercial ALD reactors are presently not equipped for in situ spectroscopy, we have constructed a model reactor that enables single-pass transmission infrared spectroscopy to be performed in situ on a layer-by-layer basis. We demonstrate the viability of this approach for the study of aluminum oxide growth on silicon surfaces, motivated by alternative gate oxide applications. Thanks to submonolayer dielectric and adsorbate sensitivity, we can quantify oxide thicknesses and hydroxyl areal densities on thermal and chemical SiO2/Si(100) substrates. Methyl formation and hydroxyl consumption upon initial trimethylaluminum (TMA) reaction can also be followed. We verify that in situ grown Al2O3 films are compatible in structure to films grown in a commercial ALD reactor.

In-situ studies in the high-voltage Electron Microscope

1990 ◽  
Vol 48 (4) ◽  
pp. 504-505
Author(s):  
K.H. Westmacott
Keyword(s):  
Phase Transitions ◽  
High Voltage ◽  
Bulk Material ◽  
Outer Region ◽  
High Energy ◽  
Research Areas ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Electron Microscopes

The principal advantages of high voltage electron microscopes are the ability to 1) attain higher resolution by virtue of the shorter wavelength, and 2) penetrate thicker specimens to observe dynamic behavior representative of bulk material. Some recent examples of in-situ HVEM research, representing the latter category, will be summarized in this contribution, and future directions discussed. Included in the most active research areas are phase transitions, deformation, high temperature reactions and environmental cell studies.Irradiation with high energy electrons in an HVEM provides a convenient alternative to thermal treatments for inducing phase transitions in alloys. An illustration of how ordering or disordering of the same material can occur under electron irradiation is shown in Figure 1. In this example, a Pt7C ordered phase was formed in a Pt-C alloy at 500°C with a defocused beam (outer region) and subsequently disordered at 30°C with a focussed beam (inner spot).

Quickest Change Point Detection in Shape Inspection of Additively Manufactured Parts Under a Multi-Resolution Framework

2020 ◽  
Author(s):  
Yu Jin ◽  
Haitao Liao ◽  
Harry Pierson
Keyword(s):  
Point Cloud ◽  
Geometric Error ◽  
Change Point Detection ◽  
Layer By Layer ◽  
Shape Inspection ◽  
The One ◽  
Alignment Errors ◽  
Point Detection

Abstract In-situ layer-by-layer inspection is essential to achieving the full capability and advantages of additive manufacturing in producing complex geometries. The shape of each inspected layer can be described by a 2D point cloud obtained by slicing a thin layer of 3D point cloud acquired from 3D scanning. In practice, a scanned shape must be aligned with the corresponding base-truth CAD model before evaluating its geometric accuracy. Indeed, the observed geometric error is attributed to systematic, random, and alignment errors, where the systematic error is the one that triggers an alarm of system anomalies. In this work, a quickest change detection (QCD) algorithm is applied under a multi-resolution alignment and inspection framework 1) to differentiate errors from different error sources, and 2) to identify the layer where the earliest systematic deviation distribution changes during the printing process. Numerical experiments and a case study on a human heart are conducted to illustrate the performance of the proposed method in detecting layer-wise geometric error.

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