UHV Microscopy of the Reconstructed Au (001) Surface

1990 ◽  
Vol 208 ◽  
Author(s):  
D. N. Dunn ◽  
L. D. Marks ◽  
J. P. Zhang
Keyword(s):  
Single Crystal ◽  
Crystal Surface ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Bulk Single Crystal ◽  
Transmission Electron ◽  
Dark Field Microscopy ◽  
Reconstructed Surface ◽  
Diffraction Patterns

ABSTRACTWe investigate the evolution of the microstructure of a reconstructed Au (001) single crystal surface using ultra high vacuum transmission electron microscopy (UHV-TEM). Bulk single crystal Au (001) surfaces were prepared via standard metallographic techniques and sputter anneal cycles. After a clean surface was obtained, the (001) surface was found to reconstruct into two nearly orthogonal domains of dimensions (5 × ∼ 20 ) along the <110> directions of the unreconstructed F.C.C. (001) surface. Transmission electron diffraction patterns (TED) and dark field microscopy are the two primary techniques used to determine the symmetry and dimensions of the reconstructed surface.

Formation Mechanisms for Multiply Twinned Particles During Nucleation in the Au/MICA System

1975 ◽  
Vol 33 ◽  
pp. 84-85
Author(s):  
Eal H. Lee ◽  
Helmut Poppa
Keyword(s):  
Deposition Time ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Formation Mechanisms ◽  
Heat Treated ◽  
Cluster Density ◽  
Diffraction Patterns ◽  
Crystal Particle ◽  
Multiply Twinned Particles

The formation of thin films of gold on mica has been studied in ultra-high vacuum (5xl0-10 torr) . The mica substrates were heat-treated for 24 hours at 375°C, cleaved, and annealed for 15 minutes at the deposition temperature of 300°C prior to deposition. An impingement flux of 3x1013 atoms cm-2 sec-1 was used. These conditions were found to give high number densities of multiple twin particles and are based on a systematic series of nucleation experiments described elsewhere. Individual deposits of varying deposition time were made and examined by bright and dark field TEM after "cleavage preparation" of highly transparent specimens. In the early stages of growth, the films generally consist of small particles which are either single crystals or multiply twinned; a strong preference for multiply twinned particles was found whenever the particle number densities were high. Fig. 1 shows the stable cluster density ns and the variation with deposition time of multiple twin particle and single crystal particle densities, respectively. Corresponding micrographs and diffraction patterns are shown in Fig. 2.

Nucleation and initial growth of Pd2Si crystals on Si(111)

1993 ◽  
Vol 51 ◽  
pp. 844-845
Author(s):  
Xianghong Tong ◽  
Oliver Pohland ◽  
J. Murray Gibson
Keyword(s):  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Initial Growth ◽  
Surface And Interface ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Initial Stage ◽  
Effect Of Surface

The nucleation and initial stage of Pd2Si crystals on Si(111) surface is studied in situ using an Ultra-High Vacuum (UHV) Transmission Electron Microscope (TEM). A modified JEOL 200CX TEM is used for the study. The Si(111) sample is prepared by chemical thinning and is cleaned inside the UHV chamber with base pressure of 1x10−9 τ. A Pd film of 20 Å thick is deposited on to the Si(111) sample in situ using a built-in mini evaporator. This room temperature deposited Pd film is thermally annealed subsequently to form Pd2Si crystals. Surface sensitive dark field imaging is used for the study to reveal the effect of surface and interface steps.The initial growth of the Pd2Si has three stages: nucleation, growth of the nuclei and coalescence of the nuclei. Our experiments shows that the nucleation of the Pd2Si crystal occurs randomly and almost instantaneously on the terraces upon thermal annealing or electron irradiation.

Pulsed U.V. Laser Cleaning Of GaSb Single Crystal Surface In Ultra-High-Vacuum

1989 ◽  
Author(s):  
E. J. Petit ◽  
V. M. Humblet ◽  
A. Brezini ◽  
R. Caudano ◽  
A. Gouskov ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Surface ◽  
High Vacuum ◽  
Laser Cleaning ◽  
Ultra High Vacuum ◽  
Single Crystal Surface

UHV-Electron Microscope Study of Monolayer Adsorption Processes

1981 ◽  
Vol 39 ◽  
pp. 204-207 ◽  
Author(s):  
K. Takayanagi
Keyword(s):  
Electron Microscopy ◽  
Dark Field ◽  
In Situ Observation ◽  
Specimen Holder ◽  
Transmission Electron ◽  
Monolayer Adsorption ◽  
Dark Field Microscopy ◽  
Tem Mode ◽  
Adsorption Processes ◽  
Reconstructed Surface

UHV electron microscopy (UHV-EM) has been shown to be a potent method for investigations of surface structures and surface processes both in TEM-TED (transmission electron microscopy and diffraction) and REM-RED (reflection EM and ED) modes. In addition to the same structural informations as RHEED and LEED they give important informations on microtopography of the surfaces and/or adsorbed phases and detailed aspects of heterogeneous surface phenomena. Analyses of Au(111) reconstructed surface structure in TEM mode and atomic steps of Si(111) surface, adsorbed structures and their domains and phase transition processes in REM mode were reported previously. The present paper reports further results of such studies. In REM mode, a new evaporator for in-situ observation of metal deposition on Si(111) and a double tilt specimen holder for diffraction analyses of surface reactions were constructed. In TEM mode, dark field microscopy by forbidden surface reflections and high resolution microscopy (HREM) have been applied.

UHV-TEM imaging of surface reconstructions in B-doped Si

1991 ◽  
Vol 49 ◽  
pp. 618-619
Author(s):  
T. S. Savage ◽  
R. Ai ◽  
L. D. Marks
Keyword(s):  
High Vacuum ◽  
Single Crystal Silicon ◽  
Ultra High Vacuum ◽  
Limiting Factor ◽  
Crystal Silicon ◽  
Transmission Electron ◽  
Surface Reconstructions ◽  
Northwestern University ◽  
Reconstructed Surface

A variety of techniques including LEED, STM and RHEED have been used to study surface reconstructions on the silicon <111> surface. Additionally, ultra high vacuum-transmission electron microscopy (UHV-TEM) has been used for a limited number of studies most notably on the 7x7 reconstructed surface. The limiting factor in these studies has been the availability of microscopes capable of in-situ sample preparation and imaging in a UHV environment. The Hitachi UHV-H9000 located at Northwestern University has recently been used to observe several surface reconstructions on a single crystal silicon <111> thin film. Transmission electron diffraction (TED) patterns were obtained for 7x7, and 5x1 surface reconstructions.

The Interaction of Bulk Defects with Surface Reconstructions

1991 ◽  
Vol 238 ◽  
Author(s):  
D. N. Dunn ◽  
L. D. Marks ◽  
K. L. Merkle
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Reconstruction ◽  
High Vacuum ◽  
Stacking Faults ◽  
Ultra High Vacuum ◽  
Bulk Single Crystal ◽  
Transmission Electron ◽  
Surface Reconstructions

ABSTRACTIt is demonstrated by ultra-high vacuum transmission electron microscopy that subsurface dislocations and stacking faults strongly interact with the Au (001) (5×n) surface reconstruction. This effect is found in both bulk single crystal and thin fílm samples.

Reconstruction of the Au (001) surface

1991 ◽  
Vol 49 ◽  
pp. 640-641
Author(s):  
D.N. Dunn ◽  
J.P. Zhang ◽  
L.D. Marks
Keyword(s):  
Electron Microscope Study ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Common Elements ◽  
Transmission Electron ◽  
Unit Cells ◽  
Transmission Electron Microscope Study ◽  
The Common ◽  
Reconstructed Surface ◽  
Surface Domains

The Au (100) surface has been a widely studied surface producing a variety of reconstructions using several different techniques. LEED has determined the clean surface reconstruction to consist of (5x20)1 and (26x68)2 surface domains. More recently an ultra high vacuum transmission electron microscope study of small Au(001) crystallites has found a reconstructed surface with (28x5)3 slightly rotated surface unit cells. The common elements in all these studies seem to be that the ‘5’ dimension is a hard dimension and does not seem to vary from study to study save one. It is also generally accepted that this surface can be thought of as the an hexagonal layer superimposed on a bulk terminated surface. Generally the long dimension is representative of an average number taken from the analysis of many domains. We have found the Au (001) surface to reconstruct into (5xn) domains where the ‘5’ dimension is a hard dimension while the ‘n’ is a soft dimension ranging between 15 and 21.

Defects in ErSi2/Si(111) epitaxial films

1990 ◽  
Vol 48 (4) ◽  
pp. 572-573
Author(s):  
C. Meneau D'Anterroches
Keyword(s):  
Lattice Mismatch ◽  
High Vacuum ◽  
Epitaxial Films ◽  
Zone Axis ◽  
Ultra High Vacuum ◽  
Epitaxial Relationship ◽  
Electronic Engineering ◽  
Transmission Electron ◽  
Diffraction Patterns

Silicides are studied in electronic engineering for their good metallic properties. Among them the group of rare earth silicides shows particular properties. Indeed, some of them, including ErSi2, crystallize in the AIB2 structure although they do not have the exact stoechiometry, their composition being about 1.7. Thus the physical properties and the influence of vacancies on the structure are studied.The film studied in this work was obtained by in-situ annealing, in ultra high vacuum, of a Si-Er film codeposited on a clean Si (111) substrate. Details are given by F. Arnaud d'Avitaya et al. The epitaxial relationship is (111 )Si//(001 )ErSi2 and (112)Si//(100)ErSi2. According to this orientation the lattice mismatch at the interface is - 1.3 %. The films were analysed using high resolution transmission electron microscopy : they are continuous when annealed at 900°C, and show some extra-spots in their diffraction patterns depending on the zone axis. Extra spots were observed along the {111} (3) and {112} zone axes, but not along {110} (4), We will focus in this paper on the {112}Si or {120}ErSi2 zone axis, the corresponding electron diffraction pattern being in Fig. 1.

Single Crystalline Nature of para-Sexiphenyl Crystallites Grown on KCl(100)

2006 ◽  
Vol 6 (3) ◽  
pp. 698-703 ◽  
Author(s):  
T. Haber ◽  
M. Oehzelt ◽  
R. Resel ◽  
A. Andreev ◽  
A. Thierry ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Dark Field ◽  
Single Crystalline ◽  
Dark Field Imaging ◽  
Transmission Electron ◽  
Crystalline Nature ◽  
Diffraction Patterns ◽  
The Individual ◽  
Single Crystalline Nature

This work focuses on studies of the single crystal nature of para-sexiphenyl structures grown on freshly cleaved KCl(100) surfaces. Two different kinds of morphologies, namely terrace like structures and needle like structures, are found by atomic force microscopy as well as by electron microscopy. Regardless of the morphology the individual crystallites show highly regular shapes. The crystalline alignment and the degree of order of the crystallites on the surface are determined by X-ray diffraction. Several epitaxial alignments of para-sexiphenyl on KCl(100) are observed and all of them are perfectly aligned on the surface. The rocking curve widths of the organic crystallites do not exceed 800″ which is approximately only the four fold of the substrates' ones. The single crystalline nature of para-sexiphenyl crystallites is proven by transmission electron microscopy, diffraction patterns, dark field imaging and high resolution techniques. Single crystalline terraced mounds reach diameters of several microns and heights of 50 nm. Single crystal needles show heights and breadths of more than 100 nm and lengths of several microns.

In-situ Microscopic Study of Cu Intragranular Electromigration

2005 ◽  
Vol 907 ◽  
Author(s):  
Kuan-Chia Chen ◽  
Chien-Neng Liao ◽  
Wen-Wei Wu ◽  
Lih-Juann Chen
Keyword(s):  
Electric Current ◽  
Crystal Orientation ◽  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Selective Area ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Atomic Image

AbstractElectromigration (EM) in unpassivated copper lines at room temperature has been investigated in ultra-high vacuum by in-situ transmission electron microscopy (TEM). The electric current induced atomic migration in a (211)-oriented Cu grain has been successfully recorded in real-time video. The atomic image of the (211) grain was found to vanish directionally when applying an electric current density of 2 × 106 A/cm2 through the Cu line. The results suggested that the combination of {111} planes and <110> directions to be the easiest EM path in crystalline copper. By performing selective area diffraction (SAD) analysis on a single Cu grain with (111) crystal orientation, some unusual electron diffraction patterns appeared after passing an electric current through the Cu line. It is believed that the EM-induced Cu twinning may be held responsible for the unique diffraction patterns

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