scholarly journals Microstructure and Nonstoichiometry of Barium Strontium Titanate thin films for dram Applications

1999 ◽  
Vol 574 ◽  
Author(s):  
S. Stemmer ◽  
S. K. Streiffer ◽  
N. D. Browning ◽  
A. I. Kingon
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Boundary Segregation ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Barium Strontium ◽  
Resolution Electron ◽  
Electrical And Dielectric Properties ◽  
Bst Films ◽  
Electron Energy Loss

AbstractIn this paper we investigate the microstructural accommodation of nonstoichiometry in (BaxSr1-x)Ti1+yO3+Z thin films grown by chemical vapor deposition. Films with three different (Ba+Sr)/Ti ratios of 49/51 (y=0.04 in the notation of the formula above), of 48/52 (y = 0.08) and of 46.5/53.5 (y=0.15), were studied. High-resolution electron microscopy is used to study the microstructure of the BST films. High-spatial resolution electron energy-loss spectroscopy (EELS) is used to reveal changes in chemistry and local atomic environment both at grain boundaries and within grains as a function of titanium excess. We find an amorphous phase at the grain boundaries and grain boundary segregation of excess titanium in the samples with y=0.15. In addition, EELS is also used to show that excess titanium is being partially accommodated in the grain interior. Implications for the film electrical and dielectric properties are outlined.

Atomie and Electron Structure of Diamond Grain boundaries in a Polycrystalline Film

1997 ◽  
Vol 472 ◽  
Author(s):  
Hideki Ichinose ◽  
Megumi Nakanose ◽  
Yaogan Zhang
Keyword(s):  
Grain Boundaries ◽  
Polycrystalline Diamond ◽  
High Resolution Electron Microscopy ◽  
Electron Structure ◽  
Polished Surface ◽  
Resolution Electron ◽  
Diamond Grain ◽  
Electron Energy Loss ◽  
Π State ◽  
Polycrystalline Diamond Film

AbstractA polycrystalline diamond film was grown on the polished surface of silicon substrate in H2-CO-O2 mixing gas. Atomic and electron structure of grain boundaries in the film was investigated by both high resolution electron microscopy and electron energy loss spectroscopy. CSL boundaries in the film showed characteristic feature in atomic structure; Σ 9 CSL boundary was parallel not to (221) plane but to (114) plane. A new line which correspond to π * state was found in addition to major σ * line in the EELS spectra of the boundary which contained three coordinate atoms. Observed π * line shows occurred change of a dangling bond (pz electron) to π state. No π * line appeared in the EELS spectra obtained from boundaries which contained no three coordinate atom such as (111) Σ 3 boundary.

High-resolution electron microscopy investigations of stacking faults in Y1Ba2Cu3O7−δ metalorganic chemical vapor deposited thin films

1999 ◽  
Vol 14 (7) ◽  
pp. 2732-2738 ◽  
Author(s):  
Ch. Grigis ◽  
S. Schamm ◽  
D. Dorignac
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Image Matching ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron ◽  
Chemical Vapor Deposited ◽  
Structural Imperfections ◽  
Metalorganic Chemical

New structural planar defects in Ba-deficient Y1Ba2Cu3O7−δ (YBCO) (1:1.6:3) thin films grown on NdGaO3 and SrTiO3 substrates by metalorganic chemical vapor deposition have been observed by means of high-resolution electron microscopy. The defects are associated with perturbations of the YBCO “1:2:3” stacking sequences along the c direction, which give rise to structural variants with locally “2:5:7,” “3:4:7,” or “4:6:10” cationic stoichiometries. The defects can be consistently interpreted as CuO–YO–CuO/CuO conversions or YO/BaO (BaO/YO) interconversions in the (a,b) planes and extending over a few nanometers along the c axis. Structural models based on image matching with simulations are proposed for two particular cases. It is thought that these structural imperfections can be effective sites of flux pinning.

Grain Boundaries of Controlled Geometry in ZnO Films Grown by Chemical Vapor Deposition: Undoped and Bi -Doped Boundaries

1995 ◽  
Vol 401 ◽  
Author(s):  
I. Majid ◽  
Y. Liu ◽  
R. W. Balluffi ◽  
J. B. Vander Sande
Keyword(s):  
Grain Boundaries ◽  
Level Structure ◽  
Chemical Vapour ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Diffusion Method ◽  
Zno Films ◽  
Resolution Electron ◽  
Chemical Vapour Deposition Technique ◽  
Crystal Films

AbstractWe describe a chemical vapour deposition technique for the controlled growth of ZnO films, containing grain boundaries which are suitable for detailed atomic resolution studies. Using this technique, we have grown; (1) random polycrystalline, (2) highly textured polycrystalline and (3) nominally single crystal films Also, a technique for doping the grain boundaries in these specimens with Bi by an “in-diffusion” method is demonstrated. The grain boundary atomic level structure and chemistry is studied by means of High Resolution Electron Microscopy (HREM) and STEM/EDX microanalysis. Some results obtained from boundaries in textured polycrystalline films which have the c-axes in neighboring grains lined-up to ˜1 ° are described.

A New Method of Preparing Tilt Boundaries for High Resolution Electron Microscopy

1987 ◽  
Vol 115 ◽  
Author(s):  
William Krakow ◽  
Victor Castańo
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Zone Axis ◽  
New Method ◽  
Lateral Overgrowth ◽  
Resolution Electron ◽  
Tilt Boundaries

ABSTRACTA new method of preparing bicrystal substrates of NaCl with a common tilt zone axis has been developed. Upon a lateral overgrowth of NaCl, bridging the two mechanically polished and oriented crystals, very thin films can then be vapor deposited. Au bicrystals of ∼ 75Å thickness and b.c.c. Cr films of similar thickness with grain boundaries have been fabricated.

Direct Correlation of Transport Properties and Microstructure In Y1Ba2Cu3O7-x Thin Film Grain Boundaries

1994 ◽  
Vol 357 ◽  
Author(s):  
B. V. Vuchic ◽  
K. L. Merkle ◽  
D. B. Buchholz ◽  
R. P. H. Chang ◽  
L. D. Marks
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Transmission Electron ◽  
Resolution Electron ◽  
Current Voltage ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
The Individual

AbstractIndividual 45° [001] tilt grain boundaries in Y1Ba2Cu3O7-x thin films grown on biepitaxial substrates were studied. The thin films were grown using both pulsed organometallic beam epitaxy (POMBE) and laser ablation. Transport characteristics of the individual grain boundaries were measured including resistance - temperature (R-T) and current - voltage (I-V) dependencies with and without an applied magnetic field. In order to elucidate possible structural origins of the differences in transport behavior, the same grain boundaries which were electrically characterized were subsequently thinned for electron-microscopy analysis. Transmission-electron-microscopy and high-resolution-electron-microscopy were used to structurally characterize the grain boundaries. The macroscopic and microscopic structures of two boundaries, a nominally resistive and a superconducting grain boundary, are compared.

Grain Boundaries In Diamond Films On Si(001)

1996 ◽  
Vol 466 ◽  
Author(s):  
D. Wittorf ◽  
C. L. Jia ◽  
W. Jäger ◽  
B. Grushko ◽  
K. Urban ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Small Angle ◽  
Large Angle ◽  
Diamond Films ◽  
Chemical Vapor ◽  
High Resolution Electron Microscopy ◽  
Dislocation Model ◽  
Crystal Lattices ◽  
Plan View ◽  
Resolution Electron

ABSTRACTGrain boundaries in [001]-oriented diamond films deposited on Si(001) by microwave-assisted chemical vapor deposition have been investigated in plan-view and cross-section samples using high-resolution electron microscopy. The poly-crystalline diamond films used in this study had large fractions of [001]-oriented grains with typical lateral dimensions of 2 μm at film thicknesses beyond 10 μm. Grains with growth orientations near (001) exhibit generally small-angle orientation deviations between their crystal lattices. Small-angle grain boundaries of symmetric and asymmetric geometry with misorientation angles below 15° are investigated in both [110]- and [001]-directions. It is found that the structures of such small-angle grain boundaries can be described by a dislocation model. These grain boundaries are on average parallel to the {110}-plane and contain in many cases micro-facets parallel to {lll}-planes. Large-angle grain boundaries with tilt angles up to 40° are also observed in interconnected films of smaller thickness. In all cases structural units with large open volumes and additional second phases are not found at the grain boundaries.

Finding the Right Problems: Some HREM Applications to Interfaces

1984 ◽  
Vol 42 ◽  
pp. 376-379
Author(s):  
D. Cherns
Keyword(s):  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Boundary Structure ◽  
Atomic Structures ◽  
Grain Boundary Structure ◽  
Resolution Electron ◽  
Point To Point ◽  
The Right ◽  
New Generation ◽  
Better Than

The use of high resolution electron microscopy (HREM) to determine the atomic structure of grain boundaries and interfaces is a topic of great current interest. Grain boundary structure has been considered for many years as central to an understanding of the mechanical and transport properties of materials. Some more recent attention has focussed on the atomic structures of metalsemiconductor interfaces which are believed to control electrical properties of contacts. The atomic structures of interfaces in semiconductor or metal multilayers is an area of growing interest for understanding the unusual electrical or mechanical properties which these new materials possess. However, although the point-to-point resolutions of currently available HREMs, ∼2-3Å, appear sufficient to solve many of these problems, few atomic models of grain boundaries and interfaces have been derived. Moreover, with a new generation of 300-400kV instruments promising resolutions in the 1.6-2.0 Å range, and resolutions better than 1.5Å expected from specialist instruments, it is an appropriate time to consider the usefulness of HREM for interface studies.

Microstructural Evaluation of Silicon Carbide Whisker Reinforced Alumina Fabricated with Carbon-Coated Whiskers

1991 ◽  
Vol 49 ◽  
pp. 920-921
Author(s):  
K. B. Alexander ◽  
P. F. Becher
Keyword(s):  
Silicon Carbide ◽  
High Resolution Electron Microscopy ◽  
Ceramic Composites ◽  
Interface Debonding ◽  
Resolution Electron ◽  
Microstructural Evaluation ◽  
Carbon Coated ◽  
Electron Energy Loss ◽  
Interfacial Films ◽  
Debonding Process

The presence of interfacial films at the whisker-matrix interface can significantly influence the fracture toughness of ceramic composites. The film may alter the interface debonding process though changes in either the interfacial fracture energy or the residual stress at the interface. In addition, the films may affect the whisker pullout process through the frictional sliding coefficients or the extent of mechanical interlocking of the interface due to the whisker surface topography.Composites containing ACMC silicon carbide whiskers (SiCw) which had been coated with 5-10 nm of carbon and Tokai whiskers coated with 2 nm of carbon have been examined. High resolution electron microscopy (HREM) images of the interface were obtained with a JEOL 4000EX electron microscope. The whisker geometry used for HREM imaging is described in Reference 2. High spatial resolution (< 2-nm-diameter probe) parallel-collection electron energy loss spectroscopy (PEELS) measurements were obtained with a Philips EM400T/FEG microscope equipped with a Gatan Model 666 spectrometer.

High-resolution electron microscopy of nanostructured materials

1995 ◽  
Vol 53 ◽  
pp. 172-173
Author(s):  
M. José-Yacamán
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
Nanostructured Materials ◽  
High Resolution Electron Microscopy ◽  
Hrem Image ◽  
Small Particles ◽  
Resolution Electron ◽  
Nanophase Materials

Electron microscopy is a fundamental tool in materials characterization. In the case of nanostructured materials we are looking for features with a size in the nanometer range. Therefore often the conventional TEM techniques are not enough for characterization of nanophases. High Resolution Electron Microscopy (HREM), is a key technique in order to characterize those materials with a resolution of ~ 1.7A. High resolution studies of metallic nanostructured materials has been also reported in the literature. It is concluded that boundaries in nanophase materials are similar in structure to the regular grain boundaries. That work therefore did not confirm the early hipothesis on the field that grain boundaries in nanostructured materials have a special behavior. We will show in this paper that by a combination of HREM image processing, and image calculations, it is possible to prove that small particles and coalesced grains have a significant surface roughness, as well as large internal strain.

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