Low Energy Point Source Electron Microscopy

1992 ◽  
Vol 295 ◽  
Author(s):  
H. J. Kreuzer
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Point Source ◽  
Carbon Fibre ◽  
Double Helix ◽  
Low Energy ◽  
Small Cluster ◽  
Image Size ◽  
Energy Point ◽  
Low Energy Electron

AbstractThe theory of the point source low energy electron microscope is reviewed. Images are calculated for a carbon fibre, a small cluster of MgO and a double helix of carbon atoms. A Kirchoff-Helmholtz transform is used for reconstruction. The importance of image size is stressed and the chemical specificity of the method is demonstrated

scholarly journals Addendum. Laplacian image contrast in mirror electron microscopy

2011 ◽  
Vol 467 (2135) ◽  
pp. 3332-3341 ◽  
Author(s):  
S. M. Kennedy ◽  
C. X. Zheng ◽  
W. X. Tang ◽  
D. M. Paganin ◽  
D. E. Jesson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Image Contrast ◽  
Low Energy ◽  
Energy Electron ◽  
Objective Lens ◽  
Imaging Geometry ◽  
Low Energy Electron ◽  
Collimated Beam

We extend the theory of Laplacian image contrast in mirror electron microscopy (MEM) to the case where the sample is illuminated by a parallel, collimated beam. This popular imaging geometry corresponds to a modern low energy electron microscope equipped with a magnetic objective lens. We show that within the constraints of the relevant approximations; the results for parallel illumination differ only negligibly from diverging MEM specimen illumination conditions.

Low Energy Electron Microscopy

1991 ◽  
Vol 237 ◽  
Author(s):  
R. M. Tromp ◽  
M. C. Reuter
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
High Vacuum ◽  
Low Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Surface And Interface ◽  
Low Energy Electron

Abstract- We have designed and built a Low Energy Electron Microscope for surface and interface studies in Ultra High Vacuum. In this paper we present major features of the design, and some of our results on surfactant mediated Ge growth on Si(001).

LOW ENERGY ELECTRON MICROSCOPY STUDIES OF THE GROWTH OF GaN ON 6H–SiC(0001)

2001 ◽  
Vol 08 (03n04) ◽  
pp. 337-346 ◽  
Author(s):  
A. PAVLOVSKA ◽  
E. BAUER
Keyword(s):  
Electron Microscopy ◽  
Experimental Data ◽  
Electron Microscope ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron

The experimental possibilities and limitations of the study of the MRE growth of GaN on 6H-SiC(0001) in a low energy electron microscope are discussed. Results illustrating these possibilities and limitations are presented. We disagree with the interpretation given in a recent report on some of the results. In this paper, we present our own interpretation of the experimental data and provide the reasons why the earlier interpretation is incorrect.

SPELEEM: Combining LEEM and Spectroscopic Imaging

1998 ◽  
Vol 05 (06) ◽  
pp. 1287-1296 ◽  
Author(s):  
Th. Schmidt ◽  
S. Heun ◽  
J. Slezak ◽  
J. Diaz ◽  
K. C. Prince ◽  
...  
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Electron Microscope ◽  
Synchrotron Radiation ◽  
Low Energy ◽  
Energy Electron ◽  
Structure Information ◽  
Low Energy Electron ◽  
Better Than

At present the only surface electron microscope which allows true characteristic XPEEM (photoemission electron microscopy using synchrotron radiation) and structural characterization is the spectroscopic LEEM developed at the Technical University Clausthal in the early nineties. This instrument has in the past been used mainly for LEEM studies of various surface and thin film phenomena, because it had very limited access to synchrotron radiation. Now the microscope is connected quasipermanently to the undulator beamline 6.2 at the storage ring ELETTRA, operating successfully since the end of 1996 under the name SPELEEM (Spectroscopic PhotoEmission and Low Energy Electron Microscope). The high brightness of the ELETTRA light source, together with an optimized instrument, results in a spatial resolution better than 25 nm and an energy resolution better than 0.5 eV in the XPEEM mode. The instrument can be used alternately for XPEEM, LEEM, LEED (low energy electron diffraction), MEM (mirror electron microscopy) and other imaging modes, depending upon the particular problem studied. The combination of these imaging modes allows a comprehensive characterization of the specimen. This is of particular importance when the chemical identification of structurar features is necessary for the understanding of a surface or thin film process. In addition, PED (photoelectron diffraction) and VPEAD (valence photoelectron angular distribution) of small selected areas give local atomic configuration and band structure information, respectively.

Low Energy Electron Microscopy for Semiconductor Applications

2008 ◽  
Vol 1088 ◽  
Author(s):  
Marian Mankos ◽  
Vassil Spasov ◽  
Liqun Han ◽  
Shinichi Kojima ◽  
Ximan Jiang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Semiconductor Device ◽  
Semiconductor Devices ◽  
Low Energy ◽  
Energy Electron ◽  
Field Of View ◽  
Dual Beam ◽  
Semiconductor Substrates ◽  
Low Energy Electron

AbstractA novel low energy electron microscope (LEEM) aimed at improving the throughput and extending the applications for semiconductor devices has been developed. A dual beam approach, where two beams with different landing energies illuminate the field of view, is used to mitigate the charging effects when the LEEM is used to image semiconductor substrates with insulating or composite (insulator, semiconductor, metal) surfaces. We have experimentally demonstrated this phenomenon by imaging a variety of semiconductor device wafers without deleterious charging effects. Results from several important semiconductor device layers will be illustrated in detail.

A New Low Energy Electron Microscope

1998 ◽  
Vol 05 (06) ◽  
pp. 1189-1197 ◽  
Author(s):  
R. M. Tromp ◽  
M. Mankos ◽  
M. C. Reuter ◽  
A. W. Ellis ◽  
M. Copel
Keyword(s):  
Electron Microscopy ◽  
Phase Transitions ◽  
Electron Microscope ◽  
Epitaxial Growth ◽  
Strain Relaxation ◽  
Low Energy ◽  
Energy Electron ◽  
Relaxation Phenomena ◽  
Low Energy Electron

Low energy electron microscopy (LEEM) has developed into one of the premier techniques for in situ studies of surface dynamical processes, such as epitaxial growth, phase transitions, chemisorption and strain relaxation phenomena. Over the last three years we have designed and constructed a new LEEM instrument, aimed at improved resolution, improved diffraction capabilities and greater ease of operation compared to present instruments.

Performance Evaluation of a Novel Type of Low-Energy Electron Microscope

1990 ◽  
Vol 48 (1) ◽  
pp. 354-355
Author(s):  
Bertholdand Senftinger ◽  
Helmut Liebl
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Field Strength ◽  
Numerical Aperture ◽  
Low Energy ◽  
Energy Electron ◽  
High Resolution Imaging ◽  
Lens System ◽  
Resolution Imaging ◽  
Low Energy Electron

During the last few years the investigation of clean and adsorbate-covered solid surfaces as well as thin-film growth and molecular dynamics have given rise to a constant demand for high-resolution imaging microscopy with reflected and diffracted low energy electrons as well as photo-electrons. A recent successful implementation of a UHV low-energy electron microscope by Bauer and Telieps encouraged us to construct such a low energy electron microscope (LEEM) for high-resolution imaging incorporating several novel design features, which is described more detailed elsewhere.The constraint of high field strength at the surface required to keep the aberrations caused by the accelerating field small and high UV photon intensity to get an improved signal-to-noise ratio for photoemission led to the design of a tetrode emission lens system capable of also focusing the UV light at the surface through an integrated Schwarzschild-type objective. Fig. 1 shows an axial section of the emission lens in the LEEM with sample (28) and part of the sample holder (29). The integrated mirror objective (50a, 50b) is used for visual in situ microscopic observation of the sample as well as for UV illumination. The electron optical components and the sample with accelerating field followed by an einzel lens form a tetrode system. In order to keep the field strength high, the sample is separated from the first element of the einzel lens by only 1.6 mm. With a numerical aperture of 0.5 for the Schwarzschild objective the orifice in the first element of the einzel lens has to be about 3.0 mm in diameter. Considering the much smaller distance to the sample one can expect intense distortions of the accelerating field in front of the sample. Because the achievable lateral resolution depends mainly on the quality of the first imaging step, careful investigation of the aberrations caused by the emission lens system had to be done in order to avoid sacrificing high lateral resolution for larger numerical aperture.

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