Additional in-depth information obtainable from the energy loss features of photoelectron peaks: the oxidation and reduction of an Fe/Cr alloy in oxygen at low partial pressures and ultra high vacuum

1990 ◽  
Vol 30 (8-9) ◽  
pp. 771-798 ◽  
Author(s):  
James E. Castle ◽  
Ruoru Ke ◽  
John F. Watts
Keyword(s):  
Energy Loss ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Depth Information ◽  
Partial Pressures

Electron energy loss spectroscopy in glancing reflection and other recent EELS developments

1983 ◽  
Vol 41 ◽  
pp. 386-387
Author(s):  
O.L. Krivanek ◽  
Y. Tanishiro ◽  
K. Yagi ◽  
R.P. Burgner
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Large Fraction ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
X Rays ◽  
Reconstruction Process ◽  
Surface Reflection ◽  
Surface Steps ◽  
Electron Energy Loss

Surface reflection images have recently revealed surface steps, surface- intersecting dislocations, and even the nature of a surface reconstruction process. While a large fraction of electrons incident on a crystal at a low angle penetrate into the bulk where they excite X-rays thus rendering glancing reflection EDXS surface insensitive, the electrons which emerge eventually penetrate typically only 10 to 30Å into the crystal, and should thus be highly sensitive as a surface probe. We have therefore investigated the suitability of glancing reflection EELS as a surface-sensitive chemical analysis technique complementary to glancing reflection imaging.The experiments were performed in a JEM 100B electron microscope modified for ultra-high vacuum (UHV) performance by the addition of liquid He cryo- pumping around the specimen, using a Gatan 607 electron energy loss spectrometer. Fig. 1 shows a series of spectra recorded for various glancing reflection conditions on clean (111) Si. It is clear that most electrons with which REM images are formed have been scattered inelastically at least once.

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.

Ultra High Vacuum Scanning Electron Microscopy of Directly Deposited Metallic Films

1971 ◽  
Vol 29 ◽  
pp. 228-229
Author(s):  
J. P. Ballantyne ◽  
C. Dix ◽  
W. C. Nixon
Keyword(s):  
Integrated Circuit ◽  
High Vacuum ◽  
Steel Specimen ◽  
Ultra High Vacuum ◽  
Main Reaction ◽  
Partial Pressures ◽  
Probe Size ◽  
Main Column ◽  
Differential Pumping ◽  
Scanning Electron

A basic scanning electron microscope of similar construction to that described by Pease and Nixon has been modified for ultra high vacuum by using a special stainless steel specimen chamber. The final aperture of the electron optical column is also the differential pumping aperture separating the lens and scan coil region from the specimen chamber. Recent further refinement has given a measured vacuum in the specimen region of 1 x 10-10 torr after baking and day to day operation at 10-8 torr. The specimen stage stability and the electron optical performance permit an electron probe size of 200-300 A at these vacuum levels. The main column is pumped to 10-6 torr.This improved vacuum performance is necessary for depositing and viewing thin metal films as there is no residual contamination and no effect of partial pressures of gases to influence the main reaction. Both silver and tin films have been deposited from halide compounds with a resulting metal thickness of about one micron giving reasonable conductivity. The substrate is silicon of integrated circuit quality.

In Situ Uhv-Tem Oxidation And Reduction Of Metals

1999 ◽  
Vol 5 (S2) ◽  
pp. 132-133
Author(s):  
J. C. Yang ◽  
M Yeadon ◽  
B. Kolasa ◽  
J. M. Gibson
Keyword(s):  
Surface Science ◽  
Materials Science ◽  
Film Growth ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Science Methods ◽  
Copper Oxidation ◽  
Transmission Electron ◽  
Partial Pressures

In this proceedings, we present a review of our experimental results of our investigations of the mechanisms of the initial stages of copper oxidation. We examined the initial stages of Cu(001) oxidation and reduction by in situ ultra-high vacuum (UHV) transmission, electron microscopy (TEM). We observed surface reconstruction and nucleation and growth of copper oxide islands. We have examined the oxidation processes from oxygen partial pressures of 10-5 torr to atmospheric pressures and temperatures from 25°C to 600°C, in order to gain fundamental insights into this important gas-metal reaction.Fundamental knowledge of gas-metal reactions, in particular oxidation, is important for a wide variety of materials science fields, such as dry corrosion, catalysis, as well as some thin film growth, such as ferroelectrics. However, there is a wide gap between information provided by surface science methods and that provided by bulk oxidation studies. The former have mostly examined the adsorption of up to ˜1ML of oxygen on the metal surface.

Progression of the Surface Roughness of N+ Silicon Epitaxial Films as Analyzed by AFM

1995 ◽  
Vol 399 ◽  
Author(s):  
S. John ◽  
E. J. Quinones ◽  
B. Ferguson ◽  
K. Pacheco ◽  
C. B. Mullins ◽  
...  
Keyword(s):  
Surface Roughness ◽  
High Vacuum ◽  
Film Surface ◽  
Chemical Vapor ◽  
Epitaxial Films ◽  
Ultra High Vacuum ◽  
Phosphorus Segregation ◽  
Surface Mobility ◽  
Partial Pressures ◽  
Effects Of Ph

ABSTRACTWe report on the morphology of heavily phosphorous doped silicon films grown by ultra high vacuum chemical vapor deposition at temperatures of ∼550° C. The effects of PH3 on epitaxial films have been examined for silicon deposited using SiH4 and Si2H6. It is found that films grown using silane experience an increase in surface roughness with increasing phosphine partial pressure. AFM and RHEED studies indicate 3-D growth. As epitaxy progresses, it is believed that phosphorus segregation on the growing film surface greatly diminishes the adsorption and surface mobility of the silicon bearing species. Initial Si deposition results in a pitted surface, but as growth advances and the phosphorus coverage increases, growth within the pits decreases the surface roughness. In contrast to SiH4, it is found that Si2H6 provides excellent quality, smooth films even at high PH3 partial pressures.

Thin Pyrolytic Graphite Films for Electron Microscope Substrates

1971 ◽  
Vol 29 ◽  
pp. 226-227 ◽  
Author(s):  
George H. N. Riddle ◽  
Benjamin M. Siegel
Keyword(s):  
Vacuum Chamber ◽  
Pyrolytic Graphite ◽  
High Vacuum ◽  
Dark Field ◽  
Ultra High Vacuum ◽  
Graphite Substrate ◽  
Nickel Substrate ◽  
Routine Procedure ◽  
Field Electron Microscopy ◽  
Dark Field Electron

A routine procedure for growing very thin graphite substrate films has been developed. The films are grown pyrolytically in an ultra-high vacuum chamber by exposing (111) epitaxial nickel films to carbon monoxide gas. The nickel serves as a catalyst for the disproportionation of CO through the reaction 2C0 → C + CO2. The nickel catalyst is prepared by evaporation onto artificial mica at 400°C and annealing for 1/2 hour at 600°C in vacuum. Exposure of the annealed nickel to 1 torr CO for 3 hours at 500°C results in the growth of very thin continuous graphite films. The graphite is stripped from its nickel substrate in acid and mounted on holey formvar support films for use as specimen substrates.The graphite films, self-supporting over formvar holes up to five microns in diameter, have been studied by bright and dark field electron microscopy, by electron diffraction, and have been shadowed to reveal their topography and thickness. The films consist of individual crystallites typically a micron across with their basal planes parallel to the surface but oriented in different, apparently random directions about the normal to the basal plane.

A High Voltage Electron Microscopy Study of Sub-Oxide Formation in Vanadium

1971 ◽  
Vol 29 ◽  
pp. 212-213
Author(s):  
R. H. Geiss ◽  
R. L. Ladd ◽  
K. R. Lawless
Keyword(s):  
High Vacuum ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Ultra High Vacuum ◽  
Pure Oxygen ◽  
Pressure Oxidation ◽  
High Voltage Electron Microscopy ◽  
Oxidation Study ◽  
Voltage Electron ◽  
Good Agreement

Detailed electron microscope and diffraction studies of the sub-oxides of vanadium have been reported by Cambini and co-workers, and an oxidation study, possibly complicated by carbon and/or nitrogen, has been published by Edington and Smallman. The results reported by these different authors are not in good agreement. For this study, high purity polycrystalline vanadium samples were electrochemically thinned in a dual jet polisher using a solution of 20% H2SO4, 80% CH3OH, and then oxidized in an ion-pumped ultra-high vacuum reactor system using spectroscopically pure oxygen. Samples were oxidized at 350°C and 100μ oxygen pressure for periods of 30,60,90 and 160 minutes. Since our primary interest is in the mechanism of the low pressure oxidation process, the oxidized samples were cooled rapidly and not homogenized. The specimens were then examined in the HVEM at voltages up to 500 kV, the higher voltages being necessary to examine thick sections for which the oxidation behavior was more characteristic of the bulk.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

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