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.

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.

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.

Bright-Field Images (Ctem) of Phase Objects at High Resolution

1976 ◽  
Vol 34 ◽  
pp. 490-491 ◽  
Author(s):  
Sumio Iijima
Keyword(s):  
High Resolution ◽  
Electron Beam Irradiation ◽  
Fine Particles ◽  
High Resolution Electron Microscopy ◽  
Good Test ◽  
Resolution Electron ◽  
Single Crystal Films ◽  
Crystal Films ◽  
By Products ◽  
Test Objects

We have developed a technique to prepare thin single crystal films of graphite for use as supporting films for high resolution electron microscopy. As we showed elsewhere (1), these films are completely noiseless and therefore can be used in the observation of phase objects by CTEM, such as single atoms or molecules as a means for overcoming the difficulties because of the background noise which appears with amorphous carbon supporting films, even though they are prepared so as to be less than 20Å thick. Since the graphite films are thinned by reaction with WO3 crystals under electron beam irradiation in the microscope, some small crystallites of WC or WC2 are inevitably left on the films as by-products. These particles are usually found to be over 10-20Å diameter but very fine particles are also formed on the film and these can serve as good test objects for studying the image formation of phase objects.

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.

Σ =13 tilt grain boundary in silicon bicrystal

1990 ◽  
Vol 48 (4) ◽  
pp. 562-563
Author(s):  
M.J. Kim ◽  
Y.L. Chen ◽  
R.W. Carpenter ◽  
J.C. Barry ◽  
G.H. Schwuttke
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Rotation Axis ◽  
Czochralski Method ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Simulation Techniques ◽  
Resolution Electron ◽  
The Common ◽  
Tilt Grain Boundary

The structure of grain boundaries (GBs) in metals, semiconductors and ceramics is of considerable interest because of their influence on physical properties. Progress in understanding the structure of grain boundaries at the atomic level has been made by high resolution electron microscopy (HREM) . In the present study, a Σ=13, (510) <001>-tilt grain boundary in silicon was characterized by HREM in conjunction with digital image processing and computer image simulation techniques.The bicrystals were grown from the melt by the Czochralski method, using preoriented seeds. Specimens for TEM observations were cut from the bicrystals perpendicular to the common rotation axis of pure tilt grain boundary, and were mechanically dimpled and then ion-milled to electron transparency. The degree of misorientation between the common <001> axis of the bicrystal was measured by CBED in a Philips EM 400ST/FEG: it was found to be less than 1 mrad. HREM was performed at 200 kV in an ISI-002B and at 400 kv in a JEM-4000EX.

scholarly journals Analysis of Stresses and Strains around Dislocations at Grain Boundaries by Quantitative High-Resolution Electron Microscopy

2006 ◽  
Vol 12 (S02) ◽  
pp. 894-895
Author(s):  
M Hytch ◽  
J-L Putaux ◽  
J Thibault
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundaries ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2006

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.

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