High-resolution REM of the reconstruction of sapphire surfaces

1991 ◽  
Vol 49 ◽  
pp. 644-645
Author(s):  
J. Liu
Keyword(s):  
High Resolution ◽  
Surface Properties ◽  
Film Growth ◽  
High Energy ◽  
Pure Oxygen ◽  
Transmission Electron ◽  
Metal Support ◽  
Sample Preparation Procedure ◽  
Reflection Electron Microscopy ◽  
Microscopy Techniques

Sapphire (α-Al2O3) is widely used in industry and research as a high temperature insulator, a substrate for growing thin films and carrier materials in catalysis. It is important to understand the surface properties of the substrate materials for thin film growth and for metal support interactions. Recently RHEED (reflection high energy electron diffraction) and REM (reflection electron microscopy) techniques have been used to characterize surface properties of sapphire annealed in air or in oxygen. The presentpaper reports some results of high resolution REM imaging of lattice fringes of reconstructed sapphire surface.The sample preparation procedure was reported elsewhere. The results presented here were obtained from a sample annealed in pure oxygen at 1650° C for 72 h. The high resolution REM observations were done in a Philips 400T transmission electron microscope operated at 120 kV with a vacuum pressure about 10-7 Torr.

RHEED investigation of oxygen-annealed sapphire surfaces

1991 ◽  
Vol 49 ◽  
pp. 630-631
Author(s):  
J. Liu ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
High Spatial Resolution ◽  
High Energy ◽  
Pure Oxygen ◽  
High Energy Electron ◽  
Transmission Electron ◽  
Surface Reconstructions ◽  
Sample Preparation Procedure ◽  
Reflection Electron Microscopy

Reflection high energy electron diffraction (RHEED) has been widely used to study surface reconstructions, surface morphology and crystal growth. In a transmission electron microscope RHEED can be combined with reflection electron microscopy (REM) to study the structures of surfaces with high spatial resolution. In this paper we report some preliminary results of RHEED investigation of the reconstruction of the oxygen annealed sapphire surfaces.The optically polished sapphire samples were obtained from Saphikon Inc. The specimens were cut, cleaned and chemically etched in boiling phosphoric acid before annealing in pure oxygen. Details of the sample preparation procedure was reported elsewhere. Oxygen annealing prevented change of surface stoichiometry and surface reactions with elements other than oxygen. The RHEED experiments were conducted in a Philips 400T transmission electron microscope operated at 120 kV with a vacuum pressure about 10-7 Torr and equipped with cold and hot stages.

The Creation and Annealing of Heavy Ion Damage in Silicon

1987 ◽  
Vol 93 ◽  
Author(s):  
L. M. Howe ◽  
M. H. Rainville
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Spatial Distribution ◽  
High Resolution ◽  
Heavy Ion ◽  
High Energy ◽  
Transmission Electron ◽  
Ion Damage ◽  
Deposited Energy ◽  
Microscopy Techniques

ABSTRACTHigh resolution transmission electron microscopy techniques have been used to obtain information on the contrast, spatial distribution, size and annealing behaviour of the damaged regions produced within individual collision cascades by heavy ion (As, Sb and Bi) bombardment (10–120 KeV) of silicon with 1.0 × 1011 – 6.0 × 1011 ions cm−2. The fraction of the theoretical cascade volume occupied by a heavily damaged region steadily increased as the average deposited energy density within the cascade increased. At high energy densities, the visible damage produced in the main cascade consisted of a single, isolated damaged region. With decreasing values of (i.e. increasing ion implant energies), there was an increasing tendency for multiple damaged regions to be produced within the main cascade.

Step structure and 5×5 restructure of annealled LaAlO3 {100} - a substrate for electroceramic thin film growth

1995 ◽  
Vol 53 ◽  
pp. 346-347
Author(s):  
Z. L. Wang ◽  
A.J. Shapiro
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Film Growth ◽  
Thin Film Growth ◽  
Transmission Electron ◽  
The Face ◽  
Reflection Electron Microscopy ◽  
Electron Microscopes ◽  
Substrate Surfaces ◽  
Microscopy Techniques

Nucleation and growth of thin films are strongly affected by the microstructures of the substrate surfaces. Although LaA1O3 {100} surfaces have been widely used as substrates for growing high Tc superconductor and ferroelectric thin films, the surface structure of the material has not been extensively analyzed using electron microscopy techniques. In this paper, reflection electron microscopy (REM) [1] is applied to examine the structures of LaA1O3 {100}. REM experiments were carried out at 300 kV and 120 kV in transmission electron microscopes. The {100} surfaces were mechanically polished and subsequently annealed at 1500 °C for 20 h in air. The LaA1O3 unit cell is the distorted-perovskite structure with lattice constant a = b = c = 0.3788 nm and α = β = γ = 90.066°, in which the La+3 ion locates at (000), the A1+3 ion at (0.5 0.5 0.5), and the O−2 ions at the face-centers {0.5 0.5 0}.

The annealed (0001) α-alumina surface and its influence on thin-film growth

1995 ◽  
Vol 53 ◽  
pp. 336-337
Author(s):  
Michael W. Bench ◽  
Paul G. Kotula ◽  
C. Barry Carter
Keyword(s):  
Electron Microscopy ◽  
Surface Energy ◽  
Film Growth ◽  
Thin Film Growth ◽  
Energy Calculations ◽  
Transmission Electron ◽  
Reflection Electron Microscopy ◽  
Low Energy Electron ◽  
Surface Nature

The growth of semiconductors, superconductors, metals, and other insulators has been investigated using alumina substrates in a variety of orientations. The surface state of the alumina (for example surface reconstruction and step nature) can be expected to affect the growth nature and quality of the epilayers. As such, the surface nature has been studied using a number of techniques including low energy electron diffraction (LEED), reflection electron microscopy (REM), transmission electron microscopy (TEM), molecular dynamics computer simulations, and also by theoretical surface energy calculations. In the (0001) orientation, the bulk alumina lattice can be thought of as a layered structure with A1-A1-O stacking. This gives three possible terminations of the bulk alumina lattice, with theoretical surface energy calculations suggesting that termination should occur between the Al layers. Thus, the lattice often has been described as being made up of layers of (Al-O-Al) unit stacking sequences. There is a 180° rotation in the surface symmetry of successive layers and a total of six layers are required to form the alumina unit cell.

Modifications of a JEOL 2000EX TEM for insSitu surface studies

1993 ◽  
Vol 51 ◽  
pp. 640-641
Author(s):  
Michael T. Marshall ◽  
Xianghong Tong ◽  
J. Murray Gibson
Keyword(s):  
Electron Diffraction ◽  
Surface Science ◽  
Film Growth ◽  
High Vacuum ◽  
High Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Transmission Electron ◽  
Fundamental Insight

We have modified a JEOL 2000EX Transmission Electron Microscope (TEM) to allow in-situ ultra-high vacuum (UHV) surface science experiments as well as transmission electron diffraction and imaging. Our goal is to support research in the areas of in-situ film growth, oxidation, and etching on semiconducter surfaces and, hence, gain fundamental insight of the structural components involved with these processes. The large volume chamber needed for such experiments limits the resolution to about 30 Å, primarily due to electron optics. Figure 1 shows the standard JEOL 2000EX TEM. The UHV chamber in figure 2 replaces the specimen area of the TEM, as shown in figure 3. The chamber is outfitted with Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES), Residual Gas Analyzer (RGA), gas dosing, and evaporation sources. Reflection Electron Microscopy (REM) is also possible. This instrument is referred to as SHEBA (Surface High-energy Electron Beam Apparatus).The UHV chamber measures 800 mm in diameter and 400 mm in height. JEOL provided adapter flanges for the column.

High-resolution transmission electron microscopy (HRTEM) observation of dislocation structures in AlN thin films

2008 ◽  
Vol 23 (8) ◽  
pp. 2188-2194 ◽  
Author(s):  
Yuki Tokumoto ◽  
Naoya Shibata ◽  
Teruyasu Mizoguchi ◽  
Masakazu Sugiyama ◽  
Yukihiro Shimogaki ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Film Growth ◽  
Threading Dislocations ◽  
Organic Vapor ◽  
Transmission Electron ◽  
Hrtem Observation ◽  
Metal Organic ◽  
Edge Dislocations

The structure and configuration of threading dislocations (TDs) in AlN films grown on (0001) sapphire by metal–organic vapor phase epitaxy (MOVPE) were characterized by high-resolution transmission electron microscopy (HRTEM). It was found that the TDs formed in the films were mainly the perfect edge dislocations with the Burgers vector of b = ⅓〈11¯20〉. The majority of the edge TDs were not randomly formed but densely arranged in lines. The arrays of the edge TDs were mainly observed on the {11¯20} and {10¯10} planes. These two planes showed different configurations of TDs. TD arrays on both of these planes constituted low-angle boundaries. We suggest that these TDs are introduced to compensate for slight misorientations between the subgrains during the film growth.

scholarly journals Structure determination of channel and transport proteins by high-resolution microscopy techniques

2011 ◽  
Vol 392 (1-2) ◽  
Author(s):  
Marcel Meury ◽  
Daniel Harder ◽  
Zöhre Ucurum ◽  
Rajendra Boggavarapu ◽  
Jean-Marc Jeckelmann ◽  
...  
Keyword(s):  
Atomic Force Microscopy ◽  
High Resolution ◽  
Transport Proteins ◽  
State Function ◽  
Oligomeric State ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron ◽  
Microscopy Techniques ◽  
High Resolution Microscopy

Abstract High-resolution microscopy techniques provide a plethora of information on biological structures from the cellular level down to the molecular level. In this review, we present the unique capabilities of transmission electron and atomic force microscopy to assess the structure, oligomeric state, function and dynamics of channel and transport proteins in their native environment, the lipid bilayer. Most importantly, membrane proteins can be visualized in the frozen-hydrated state and in buffer solution by cryo-transmission electron and atomic force microscopy, respectively. We also illustrate the potential of the scintillation proximity assay to study substrate binding of detergent-solubilized transporters prior to crystallization and structural characterization.

scholarly journals Ghost imaging with electron microscopy inspired, non-orthogonal phase masks

2021 ◽  
Author(s):  
Akhil Kallepalli ◽  
Daan Stellinga ◽  
Ming-Jie Sun ◽  
Richard Bowman ◽  
Enzo Rotunno ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
High Energy ◽  
Reconstruction Method ◽  
Ghost Imaging ◽  
Light Modulator ◽  
Transmission Electron ◽  
Resolution Imaging ◽  
Electron Microscopes ◽  
Energy Processes

Abstract Transmission electron microscopes (TEM) achieve high resolution imaging by raster scanning a focused beam of electrons over the sample and measuring the transmission to form an image. While a TEM can achieve a much higher resolution than optical microscopes, they face challenges of damage to samples during the high energy processes involved. Here, we explore the possibility of applying computational ghost imaging techniques adapted from the optical regime to reduce the total, required illumination intensity. The technological lack of the equivalent high-resolution, optical spatial light modulator for electrons means that a different approach needs to be pursued. Using the optical equivalent, we show that a simple six-needle charged device to modulate the illuminating beam, alongside a novel reconstruction method to handle the resulting highly non-orthogonal patterns, is capable of producing images comparable in quality to a raster-scanned approach with much lower peak intensity.

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