Grain boundary faceting in YBa2Cu3O7–x bicrystal thin films on SrTiO3 substrates

2002 ◽  
Vol 17 (2) ◽  
pp. 323-335 ◽  
Author(s):  
Qiang Jin ◽  
Siu-Wai Chan
Keyword(s):  
Thin Films ◽  
Boundary Plane ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Film Boundary ◽  
Lattice Images ◽  
Tilt Boundaries ◽  
The Difference ◽  
Straight Segments ◽  
Misorientation Angles

The structure of [001] tilt boundaries in YBa2Cu3O7–x (YBCO) thin films deposited on [001] tilt SrTiO3 (STO) bicrystal substrates has been characterized by transmission electron microscopy (TEM). These boundaries are (100)/(210), (310)/(510), (410)/(310), (510)/(210), (210)/(410), and (210)/(310), with corresponding misorientation angles of 26°, 29°, 32°, 37°, 40°, and 44°. It was found that the YBCO film boundaries were meandering along the relatively straight substrate boundaries. High-resolution lattice images indicated that the microscopic meandering of the film boundary essentially consisted of many straight segments of facets at the atomic scale. On the basis of the observed facets, three competing factors controlling the formation of facets are discussed. First, the boundary plane is defined by Miller indices (hk0) in both crystals with sufficiently small h, k (i.e., h, k ≤ 5) and sufficiently large effective interplanar spacing (i.e., deff > 0.06 nm). Second, the closure failure defined by the difference between the local misorientation from the design misorientation is small, i.e., less than 2°. Third, the deviation of a local facet plane is observed to be less than 30° from the design boundary plane. Higher values of deffs are observed to give tolerance to higher deviation angles.

High Resolution Transmission Electron Microscopy of GaAs/AlAs Hetero-Structures in the Projection

1990 ◽  
Vol 183 ◽  
Author(s):  
N. Ikarashi ◽  
A. Sakai ◽  
T. Baba ◽  
K. Ishida ◽  
J. Motohisa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Atomic Scale ◽  
Transmission Electron ◽  
Interfacial Structures ◽  
Focus Condition ◽  
Lattice Images ◽  
The Difference ◽  
Imaging Conditions

AbstractHigh resolution transmission electron microscopy (HRTEM) of GaAs/AlAs hetero-structures grown by molecular beam epitaxy (MBE) is carried out in the <110> projection. It is shown that GaAs and AlAs are distinguished clearly by the difference in their lattice images at the samples thicknesses of about 15–30 nm under near Scherzer focus condition. Under these imaging conditions, very thin films consist of single monolayer AlAs are observed. Vicinal interfaces of GaAs/AlAs which were grown on (001) substrate misoriented toward [110] are also examined in the [110] projection. The interfacial structures are imaged edgeon, so that the fluctuations of terrace width, and the roughness of step-edges at these interfaces are observed on an atomic scale.

Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

1994 ◽  
Vol 52 ◽  
pp. 796-797
Author(s):  
J. L. Lee ◽  
C. A. Weiss ◽  
R. A. Buhrman ◽  
J. Silcox
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thin Films ◽  
Scanning Transmission Electron Microscope ◽  
Atomic Scale ◽  
Island Growth ◽  
Multilayer Systems ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

Effects of dopant concentration on the microstructure of tin- doped indium oxide thin films

1990 ◽  
Vol 48 (4) ◽  
pp. 716-717
Author(s):  
I. A. Rauf
Keyword(s):  
Thin Films ◽  
Indium Oxide ◽  
Ionic Radius ◽  
Free Carrier ◽  
Electron Gun ◽  
Periodic Lattice ◽  
Oxide Thin Films ◽  
Transmission Electron ◽  
The Difference ◽  
Dopant Atoms

To understand the electronic conduction mechanism in Sn-doped indium oxide thin films, it is important to study the effect of dopant atoms on the neighbouring indium oxide lattice. Ideally Sn is a substitutional dopant at random indium sites. The difference in valence (Sn4+ replaces In3+) requires that an extra electron is donated to the lattice and thus contributes to the free carrier density. But since Sn is an adjacent member of the same row in the periodic table, the difference in the ionic radius (In3+: 0.218 nm; Sn4+: 0.205 nm) will introduce a strain in the indium oxide lattice. Free carrier electron waves will no longer see a perfect periodic lattice and will be scattered, resulting in the reduction of free carrier mobility, which will lower the electrical conductivity (an undesirable effect in most applications).One of the main objectives of the present investigation is to understand the effects of the strain (produced by difference in the ionic radius) on the microstructure of the indium oxide lattice when the doping level is increased to give high carrier densities. Sn-doped indium oxide thin films were prepared with four different concentrations: 9, 10, 11 and 12 mol. % of SnO2 in the starting material. All the samples were prepared at an oxygen partial pressure of 0.067 Pa and a substrate temperature of 250°C using an Edwards 306 coating unit with an electron gun attachment for heating the crucible. These deposition conditions have been found to give optimum electrical properties in Sn-doped indium oxide films. A JEOL 2000EX transmission electron microscope was used to investigate the specimen microstructure.

Microstructure of SrTiO3 Thin Films as Single Layer and Incorporated in Yba2Cu3O7-x/SrTiO3 Multilayers

1995 ◽  
Vol 401 ◽  
Author(s):  
L. Ryen ◽  
E. Olssoni ◽  
L. D. Madsen ◽  
C. N. L. Johnson ◽  
X. Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Lattice Mismatch ◽  
Single Layer ◽  
Transmission Electron ◽  
Tilt Boundaries ◽  
Interfacial Dislocations ◽  
The Individual ◽  
Film Substrate

AbstractEpitaxial single layer (001) SrTiO3 films and an epitaxial Yba2Cu3O7-x/SrTiO3 multilayer were dc and rf sputtered on (110)rhombohedral LaAIO3 substrates. The microstructure of the films was characterised using transmission electron microscopy. The single layer SrTiO3 films exhibited different columnar morphologies. The column boundaries were due to the lattice mismatch between film and substrate. The boundaries were associated with interfacial dislocations at the film/substrate interface, where the dislocations relaxed the strain in the a, b plane. The columns consisted of individual subgrains. These subgrains were misoriented with respect to each other, with different in-plane orientations and different tilts of the (001) planes. The subgrain boundaries were antiphase or tilt boundaries.The individual layers of the Yba2Cu3O7-x/SrTiO3 multilayer were relatively uniform. A distortion of the SrTiO3 unit cell of 0.9% in the ‘001’ direction and a Sr/Ti ratio of 0.62±0.04 was observed, both in correspondence with the single layer SrTiO3 films. Areas with different tilt of the (001)-planes were also present, within each individual SrTiO3 layer.

Structure and Dissociation of 15° Tilt Boundaries in Germanium

1983 ◽  
Vol 25 ◽  
Author(s):  
W. Skrotzki ◽  
H. Wendt ◽  
C. B. Carter ◽  
D. L. Kohlstedt
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Boundary ◽  
Czochralski Method ◽  
Boundary Plane ◽  
First Order ◽  
Grain Boundary Plane ◽  
Transmission Electron ◽  
Theoretical Predictions ◽  
Tilt Boundaries

ABSTRACTThe structure and dissociation of grain boundaries in Ge bicrystals, grown by the Czochralski method, have been analyzed by visible light and transmission electron microscopy. The seed crystals were oriented to yield either a symmetric or an asymmetric grain boundary plane with a 15° rotation about a common <110> direction. The asymmetric boundary, with a {111} boundary plane, dissociated along most of its length into a first order twin boundary (Σ 3) and a symmetric 55° grain boundary (Σ 41c). The symmetric 15° boundary is composed of an array of Lomer dislocations. Contrary to theoretical predictions, this boundary is stable.

Island Coalescence Induced Substructure Within GaP Epitaxial Layers Grown on (001), (111), (110) and (113) Si

2000 ◽  
Vol 618 ◽  
Author(s):  
V. Narayanan ◽  
S. Mahajan ◽  
K. J. Bachmann ◽  
V. Woods ◽  
N. Dietz
Keyword(s):  
Defect Formation ◽  
Chemical Beam Epitaxy ◽  
Inversion Domain ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Lattice Images ◽  
Tilt Boundaries ◽  
Island Coalescence ◽  
Inversion Domain Boundaries ◽  
Multiple Twinning

ABSTRACTGaP islands grown on selected surfaces of Si and their coalescence behavior have been investigated by transmission electron microscopy. These layers were grown by chemical beam epitaxy. A number of significant observations emerge from this study. First, planar defect formation has been shown to be related to stacking errors on the smaller P-terminated {111} facets of GaP islands. Amongst the four orientations, (111) epilayers have a higher density of stacking faults and first order twins because of more P-terminated {111} facets per island. Second, multiple twinning on exposed {111} facets can produce tilt boundaries and irregular growths when islands coalesce. Third, inversion domain boundaries lying on {110} planes have been shown to form during GaP island coalescence across monatomic steps on (001) Si. Image simulations have been performed to show that these boundaries can be seen in high resolution lattice images and the observed contrast is attributed to the presence of wrong Ga-Ga and P-P bonds at the inversion boundary.

Microstructural Studies of Ferroelectric Bi2VO5.5 Thin Films With LaNiO3 Electrodes

1994 ◽  
Vol 341 ◽  
Author(s):  
D. Prasad Beesabathina ◽  
L. Salmanca-Riba ◽  
M. S. Hegde ◽  
K. M. Satyalakshmi ◽  
K. V. R. Prasad ◽  
...  
Keyword(s):  
Thin Films ◽  
Growth Direction ◽  
Buffer Layers ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Transmission Electron ◽  
Lattice Images ◽  
Relationship Of ◽  
Microstructural Studies

AbstractThin films of Bi2VO5.5 (BVO), a vanadium analog of the n = I member of the Aurivillius family, have been prepared by pulsed laser deposition. The BVO films grow along the [001] direction on LaNiO3(LNO) and YBa2Cu3O7 (YBCO) electrode buffer layers on LaA- IO3(LAO) substrates as obtained from X-ray diffraction studies. The microstructure of the films and of the interfaces within the film and between the film and the substrate were characterized using transmission electron microscopy. The in-plane epitaxial relationship of the rhombohedral LNO on perovskite LAO was [100] LNO // [100] LAO and [001] LNO // [001] LAO. High resolution lattice images showed a sharp interface between LNO and LAO. However, the LNO film is twinned with a preferred orientation along the growth direction. The BVO layer is single crystalline on both LNO/LAO and YBCO/LAO with the caxis parallel to the growth direction except for a thin layer of about 400 Å at the interface which is polycrystalline.

In-Plane Ferroelectricity in Strontium Titanate Thin Films

2003 ◽  
Vol 783 ◽  
Author(s):  
K. F. Astafiev ◽  
V. O. Sherman ◽  
M. Cantoni ◽  
A. K. Tagantsev ◽  
N. Setter ◽  
...  
Keyword(s):  
Thin Films ◽  
Low Temperatures ◽  
Ferroelectric Phase ◽  
Pulsed Laser ◽  
Hysteresis Loops ◽  
Laser Deposition ◽  
Polarization Response ◽  
Transmission Electron ◽  
The Difference ◽  
Electrical Characterizations

ABSTRACTThe results of structural and electrical characterizations of SrTiO3 thin films deposited onto LaAlO3 substrates by pulsed laser deposition technique are presented. The appearance of the ferroelectric phase in these films has been experimentally documented, the transition temperature being in the range of 90–120K. The hysteresis loops have been monitored in a wide temperature range by using thin film planar capacitors, the driving field being predominantly in the plane of the film. The switching properties of the films has been studied at low temperatures (∼25K) and well saturated loops have been observed with relatively low coercive field (<6kV/cm for 10μm gap). The presence of the imprint phenomenon has been also found at low temperatures.The microstructure of the investigated SrTiO3 thin films has been studied by using a high resolution transmission electron microscope (TEM). It has been found that the annealed and as-deposited thin films, being of the same composition, have quite different microstructures. The difference observed in the polarization response of the films is related to that in their microstructure.

Dynamic Atomic Mechanisms of Plasticity of Ni Nanowires and Nano Crystalline Ultra-Thin Films

2010 ◽  
Vol 654-656 ◽  
pp. 2293-2296 ◽  
Author(s):  
Xiao Dong Han ◽  
Li Hua Wang ◽  
Pan Liu ◽  
Yong Hai Yue ◽  
Ming Jie Yang ◽  
...  
Keyword(s):  
Thin Films ◽  
Large Strain ◽  
Atomic Scale ◽  
Nano Crystalline ◽  
Transmission Electron ◽  
Strain Plasticity ◽  
Large Strain Plasticity ◽  
Microscopy Techniques ◽  
Mechanisms Of Plasticity

Using our recently developed in situ transmission electron microscopy techniques, we revealed that the FCC structured Ni nanowires with diameter of about 30 nm possess ultra-large strain plasticity. Dynamic complex dislocation activities mediated the large strain bent-plasticity and they were monitored at atomic scale in real time. The bent-induced strain gradient allows studying the strain effects on dislocation mediated plasticity. We also explored the deformation techniques to more general cases, the nano thin films. An example of tensile Pt ultra-thin film is presented.

Structure of high-angle-tilt boundaries in YBa2Cu3-O7-x thin films

1991 ◽  
Vol 49 ◽  
pp. 1086-1087
Author(s):  
D. H. Shin ◽  
J. Silcox ◽  
S. E. Russek ◽  
D. K. Lathrop ◽  
B. H. Moeckly ◽  
...  
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Weak Link ◽  
Boundary Region ◽  
Atomic Scale ◽  
High Resolution Imaging ◽  
High Angle ◽  
Superconducting Properties ◽  
Tilt Boundaries ◽  
Resolution Imaging

It has been known that high angle tilt grain boundaries in c-axis oriented YBa2Cu3O7-x thin films cause weak link behavior in the transport properties reducing Jc's by several orders of magnitude. These grain boundaries have been shown to be clean both structurally and chemically by high resolution imaging and microanalysis studies. Therefore the mechanism of weak link behavior in thin film YBa2Cu3O7-x is not yet understood.Recently it has been deduced from the behavior of weak link Jc under small magnetic fields that the high angle tilt boundaries are nonuniform, consisting of several regions of good contact, each about 5-10 % of the boundary length, with the rest of the boundary region being poor. This seems to suggest that the superconducting properties at the boundary may be sensitive to changes in structures of atomic scale, since typical grain boundaries are free of macroscopic (≥ 10 Å) defects all along the boundaries.

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