A theory of contamination in electron microscopes by surface diffusion

1978 ◽  
Vol 36 (1) ◽  
pp. 116-117
Author(s):  
J.T. Fourie
Keyword(s):  
Electron Beam ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Physical Parameters ◽  
Carbon Compounds ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Primary Electrons ◽  
Long Chain

Contamination in electron microscopes can be a serious problem in STEM or in situations where a number of high resolution micrographs are required of the same area in TEM. In modern instruments the environment around the specimen can be made free of the hydrocarbon molecules, which are responsible for contamination, by means of either ultra-high vacuum or cryo-pumping techniques. However, these techniques are not effective against hydrocarbon molecules adsorbed on the specimen surface before or during its introduction into the microscope. The present paper is concerned with a theory of how certain physical parameters can influence the surface diffusion of these adsorbed molecules into the electron beam where they are deposited in the form of long chain carbon compounds by interaction with the primary electrons.

Reduction of Specimen Contamination in Electron-Beam Instruments

1976 ◽  
Vol 34 ◽  
pp. 576-577
Author(s):  
G. Lehmpfuhl ◽  
P. J. Smith
Keyword(s):  
Electron Beam ◽  
Cold Trap ◽  
Beam Diameter ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Combination Of Methods ◽  
Convergent Beam ◽  
Very High

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.

AlN thin films fabricated by ultra-high vacuum electron-beam evaporation with ammonia for silicon-on-insulator application

2005 ◽  
Vol 239 (3-4) ◽  
pp. 327-334 ◽  
Author(s):  
Ming Zhu ◽  
Peng Chen ◽  
Ricky K.Y. Fu ◽  
Weili Liu ◽  
Chenglu Lin ◽  
...  
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
High Vacuum ◽  
Electron Beam Evaporation ◽  
Silicon On Insulator ◽  
Ultra High Vacuum

In situ quantitative analysis of GeXSi1-X alloys during growth by reflection EELS

1991 ◽  
Vol 49 ◽  
pp. 878-879
Author(s):  
Shouleh Nikzad ◽  
Channing C. Ahn ◽  
Harry A. Atwater
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Film Growth ◽  
High Vacuum ◽  
High Energy ◽  
Ultra High Vacuum ◽  
Mbe Growth ◽  
Electron Microscopes ◽  
Electron Energy Loss

The universality of reflection high energy electron diffraction (RHEED) as a structural tool during film growth by molecular beam epitaxy (MBE) brings with it the possibility for in situ surface chemical analysis via spectroscopy of the accompanying inelastically scattered electrons. We have modified a serial electron energy loss spectrometer typically used on an electron microscope to work with a 30 keV RHEED-equipped MBE growth chamber in order to determine the composition of GexSi1-x alloys by reflection electron energy loss (REELS) experiments. Similar work done in transmission electron microscopes has emphasized the surface sensitivity of this technique even though these experiments have never been done under ultra-high vacuum conditions. In this work, we are primarily concerned with the accuracy with which core losses can be used to determine composition during MBE growth.

Initial Oxidation Kinetics of Cu(100), (110), and (111) Thin Films Investigated by in Situ Ultra-high-vacuum Transmission Electron Microscopy

2005 ◽  
Vol 20 (7) ◽  
pp. 1684-1694 ◽  
Author(s):  
Guangwen Zhou ◽  
Judith C. Yang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Surface Diffusion ◽  
High Vacuum ◽  
Nucleation And Growth ◽  
Ultra High Vacuum ◽  
Initial Oxidation ◽  
Transmission Electron ◽  
Oxygen Surface

The initial oxidation stages of Cu(100), (110), and (111) surfaces have been investigated by using in situ ultra-high-vacuum transmission electron microscopy (TEM) techniques to visualize the nucleation and growth of oxide islands. The kinetic data on the nucleation and growth of oxide islands shows a highly enhanced initial oxidation rate on the Cu(110) surface as compared with Cu(100), and it is found that the dominant mechanism for the nucleation and growth is oxygen surface diffusion in the oxidation of Cu(100) and (110). The oxidation of Cu(111) shows a dramatically different behavior from that of the other two orientations, and the in situ TEM observation reveals that the initial stages of Cu(111) oxidation are dominated by the nucleation of oxide islands at temperatures lower than 550 °C, and are dominated by two-dimensional oxide growth at temperatures higher than 550 °C. This dependence of the oxidation behavior on the crystal orientation and temperature is attributed to the structures of the oxygen-chemisorbed layer, oxygen surface diffusion, surface energy, and the interfacial strain energy.

Electron-Beam Recrystallization of Silicon Layers on Silicon Dioxide

1983 ◽  
Vol 23 ◽  
Author(s):  
Tomoyasu Inoue ◽  
Kenji Shibata ◽  
Koichi Kato ◽  
Toshio Yoshii ◽  
Iwao Higashinakagawa ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Vacuum ◽  
Silicon Layer ◽  
Sample Surface ◽  
Ultra High Vacuum ◽  
High Frequency Oscillation ◽  
Transient Temperature ◽  
Large Area ◽  
Very High Frequency ◽  
Very High

ABSTRACTRecent progress of SOI growth by electron beam recrystallization is described. Transient temperature profile on the recrystallizing sample surface was analyzed experimentally by direct observation with a thermovision, which is essential for the understanding of crystal growith mechanism. SOI growth was performed by a spot beam annealing and a pseudo-line shaped beam annealing. The line shaped electron beam has been proved to be useful for large area crystallization.Emphasis was placed on lateral seeded recrystallization of silicon layer evaporated in an ultra high vacuum. Silicon layers with the seed area grown epitaxially during the evaporation and above 1 μm thickness were successfully recrystallized, resulting in reproducible lateral epitaxiy. The pseudo-line shaped electron beam formed by very high frequency oscillation enabled dimensional enlargement of lateral epitaxial growth. crystalline properties were characterized by analyses of Rutherford backscattering and electron channeling pattern.

Reflection Electron Microscopy (REM) of Surface Steps & Dislocations on GaP(110) & GaAs(110)

1982 ◽  
Vol 40 ◽  
pp. 450-451
Author(s):  
Tung Hsu ◽  
Sumio Iijima
Keyword(s):  
Electron Microscopy ◽  
Room Temperature ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Heating Stage ◽  
Surface Steps ◽  
Reflection Electron Microscopy ◽  
Electron Microscopes ◽  
High Vacuum Environment

Reflection electron microscopy (REM) in ultra high vacuum environment with heating stage has been reported by Osakabe, et al. In this paper, we present our results in REM imaging of single steps and dislocations using commercial electron microscopes (JEM-100B and Philips-400T) under ordinary pressure (10-7 torr) and room temperature.

Development of fast heating electron beam annealing setup for ultra high vacuum chamber

2014 ◽  
Vol 85 (2) ◽  
pp. 025107 ◽  
Author(s):  
Sadhan Chandra Das ◽  
Abhijit Majumdar ◽  
Sumant Katiyal ◽  
T. Shripathi ◽  
R. Hippler
Keyword(s):  
Electron Beam ◽  
Vacuum Chamber ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Fast Heating ◽  
High Vacuum Chamber ◽  
Ultra High Vacuum Chamber

Electron induced surface reactions of (η5-C5H5)Fe(CO)2Mn(CO)5, a potential heterobimetallic precursor for focused electron beam induced deposition (FEBID)

2018 ◽  
Vol 20 (11) ◽  
pp. 7862-7874 ◽  
Author(s):  
Ilyas Unlu ◽  
Julie A. Spencer ◽  
Kelsea R. Johnson ◽  
Rachel M. Thorman ◽  
Oddur Ingólfsson ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Electron Beam ◽  
Photoelectron Spectroscopy ◽  
Surface Reactions ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
X Ray ◽  
Electron Beam Induced Deposition

Electron-induced surface reactions of (η5-C5H5)Fe(CO)2Mn(CO)5were exploredin situunder ultra-high vacuum conditions using X-ray photoelectron spectroscopy and mass spectrometry.

A New High Resolution Field Emission SEM with Variable Pressure Capabilities

2001 ◽  
Vol 7 (S2) ◽  
pp. 880-881 ◽  
Author(s):  
Peter Gnauck ◽  
Volker Drexel ◽  
J. Greiser
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Low Voltage ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Chamber Pressure ◽  
Variable Pressure ◽  
Natural State ◽  
Electron Microscopes ◽  
Scanning Electron

To examine non conductive samples in their natural state (i.e. without significant sample preparation) at high resolution in the SEM the technique of low voltage field emission scanning electron microscopy (LVFESEM) is used. Due to the limitation in accelerating voltage (U<1kV) this technique is limited in respect of chemical analysis. Furthermore it is not possible to examine humid and outgassing samples in high vacuum. in recent years the application of variable pressure scanning electron microscopes (VPSEM) became an important technique in materials science as well as in life science. Due to the capability of maintaining a high chamber pressure humid, outgassing and non-conductive samples, can be examined in their natural state without significant sample modification or preparation. Especially compound materials with different electron yields can be imaged without any charging effects (Fig. 2), [2]. This paper describes a high resolution field emission electron microscope, that combines low voltage and variable pressure capabilities.The high pressure capabilities of the instrument are realized by eliminating the high vacuum requirements of SEM in the microscope chamber. This is done by separating the vacuum environment in the chamber from the ultra high vacuum environment in the gun area.

An Ultra High Vacuum Modular Electron Beam System

1971 ◽  
Vol 29 ◽  
pp. 20-21
Author(s):  
F. Christiansen
Keyword(s):  
High Vacuum ◽  
Ultra High Vacuum ◽  
Modular Construction ◽  
X Ray ◽  
Beam System ◽  
Transmission Electron ◽  
Common Foundation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Traditionally, x-ray microprobes, scanning electron microscopes and similar electron microbeam instruments have been designed and built in much the same manner as transmission electron microscopes; that is, as single purpose instruments with provisions for a miltiplicity of attachments to increase their scope. Electron optically these instruments are nearly identical, the only differences being in mechanical restrictions necessary to accommodate spectrometers, specimen stages, light optics, etc. Hence, it appears desirable to modularize an electron microbeam system to provide a variety of instruments, each sharing a common foundation. This then allows the user to convert an instrument from one configuration to another at minimum expense without sacrificing performance and also to readily construct specialized instruments from standard parts. Other advantages of modular construction, both from the builders' and users' standpoint have been discussed previously.

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