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).

Stress-induced structures on surfaces observed using Scanning Tunneling Microscopy and low-energy Electron Microscopy

1992 ◽  
Vol 50 (1) ◽  
pp. 332-333
Author(s):  
Ellen D. Williams ◽  
R.J. Phaneuf ◽  
N.C. Bartelt ◽  
W. Swiech ◽  
E. Bauer
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Scanning Tunneling Microscopy ◽  
High Vacuum ◽  
Finite Size ◽  
Low Energy ◽  
Energy Electron ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron

Elastic stresses play a well-known and important role in the structure of thin films during growth. However, elastic effects can also greatly influence surface morphology of the substrate. One source of this influence, as has long been recognized is the elastic interactions between steps on surfaces. More recently, Marchenko has shown that surface stress can stabilize finite-size structures in surfaces, such as facets. Traditionally surface morphologies such as steps and facets have been measured by low-energy electron diffraction. However, the more recent development of ultra-high vacuum compatible microscopic techniques such as scanning tunneling microscopy, reflection electron microscopy, and low-energy electron microscopy, now make it possible to image steps and facets directly to obtain information about sizes and size distributions. This information in turn makes it possible to test the influence of stress on surface morphology directly.

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 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.

Mirror Electron Microscope-Low Energy Electron Diffraction for Studies of Surface Ordering and Melting

1990 ◽  
Vol 208 ◽  
Author(s):  
W. N. Unertl ◽  
C. S. Shern
Keyword(s):  
Electron Diffraction ◽  
Surface Potential ◽  
High Vacuum ◽  
Normal Incidence ◽  
Low Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Objective Lens ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron

ABSTRACTMirror Electron Microscopy – Low Energy Electron Diffraction (MEMLEED) combines a LEED with MEM in a single simple instrument for studies of surface processes such as phase transitions and premelting under ultra-high vacuum (uhv) conditions. In MEMLEED, 5–20 keV primary electrons are decelerated by an electrostatic mirror-objective lens in which the sample is the mirror element. In the MEN mode, electrons are reflected just above the surface, reaccelerated through the objective lens and imaged. Contrast is due to variations in both surface potential and topography. Current uhv instruments have lateral resolution of about 1 μm. In the LEED mode, 0-100 eV electrons strike the sample at near normal incidence. Diffracted electrons are accelerated through the objective lens. Beam spacings in the imaged diffraction pattern are proportional to k11 and beams do not move as the incident energy is varied. MEMLEED has intrinsically higher transfer width and is less sensitive to magnetic fields near the sample than conventional LEED. Design considerations for uhv instruments are discussed. Applications to the study of order-disorder transitions, premelting phenomena, and to measurements of changes in surface potential are described.

Auger electron spectroscopy and microscopy in STEM

1991 ◽  
Vol 49 ◽  
pp. 464-465
Author(s):  
Gary G. Hembree ◽  
Frank C. H. Luo ◽  
John A. Venables
Keyword(s):  
Auger Electron Spectroscopy ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
High Vacuum ◽  
Low Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Secondary Electrons ◽  
Excitation Beam ◽  
Low Energy Electron

Spatial resolution in Auger electron spectroscopy (AES) is primarily a function of the excitation beam current distribution. For highest resolution the question of how to produce such a small probe of electrons is coupled with how to extract the secondary electrons efficiently from the sample. Kniit and Venables have shown the optimum configuration for highest resolution AES is a combination of a magnetic immersion lens, additional solenoids (“parallelizers“) to shape the weak magnetic field in the low energy electron transport region and a concentric hemispherical analyzer (CHA) to disperse and detect the secondary electrons. This combination has been incorporated into a new ultra-high vacuum STEM at ASU, along with the low energy electron optics required to interface the magnetic collection system with the CHA.

scholarly journals Surface crystallography with low-energy electron diffraction

1993 ◽  
Vol 442 (1914) ◽  
pp. 61-72
Keyword(s):  
Electron Diffraction ◽  
High Vacuum ◽  
High Energy ◽  
Low Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
X Ray ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Surface Crystallography

Bragg’s 1913 publication of the principles of X-ray crystallography came only a year after von Laue’s discovery of X-ray diffraction from crystals. Structure determination (of small molecules) with high-energy electron diffraction followed by just three years the 1927 discovery of electron diffraction by Davisson and Germer. By contrast, low-energy electron diffraction (LEED) would require four more decades before yielding its first structure determinations (of surfaces) around 1970. The delay was primarily due to the need for ultra-high vacuum and to a lesser extent to the need for a suitable theory to model multiple scattering. This review will sketch the development of surface crystallography by LEED and describe its principles and present capabilities.

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.

scholarly journals Growth of germanium on Au(111): formation of germanene or intermixing of Au and Ge atoms?

2017 ◽  
Vol 19 (28) ◽  
pp. 18580-18586 ◽  
Author(s):  
Esteban D. Cantero ◽  
Lara M. Solis ◽  
Yongfeng Tong ◽  
Javier D. Fuhr ◽  
María Luz Martiarena ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Scanning Tunneling Microscopy ◽  
High Vacuum ◽  
Low Energy ◽  
Energy Electron ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron

We studied the growth of Ge layers on Au(111) under ultra-high vacuum conditions from the submonolayer regime up to a few layers with Scanning Tunneling Microscopy (STM), Direct Recoiling Spectroscopy (DRS) and Low Energy Electron Diffraction (LEED).

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