Low-energy electron-induced decarbonylation of Fe(CO)5 films adsorbed on Au(111) surfaces

2011 ◽  
Vol 89 (10) ◽  
pp. 1163-1173 ◽  
Author(s):  
Christelle Hauchard ◽  
Paul A. Rowntree
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Protective Layer ◽  
Incident Beam ◽  
High Sensitivity ◽  
Grazing Incidence ◽  
Film Structure ◽  
Low Energy ◽  
Structural Motif ◽  
Incident Electron Energy

The decarbonylation of Fe(CO)5 adsorbed in monolayer and multilayer films on Au(111)/mica substrates has been induced by 0–20 eV electrons and studied by grazing incidence IR spectroscopy. Our results show that the cross sections for the initial stages of this process in as-deposited films range from 60–300 Å2 and show considerable variations with the incident electron energy. The high sensitivity to low-energy electrons is believed to be the result of secondary reactions of anion fragments in the film with the neighbouring Fe(CO)5 moieties, leading to increasingly massive heteronuclear Fen(CO)m species and progressive CO elimination. Continued exposure to the electron beam leads to the slower degradation of these newly created species into an Fe-rich deposit containing traces of CO. These traces are removed by subsequent heating to ~300 K. Fe(CO)5 films that have been subjected to temperatures exceeding 125 K have no measurable sensitivity to the electron beam in the 0–20 eV regime; this is believed to be due to the structural transformation of the as-deposited thin film structure into 3D aggregates. This structural motif presents a very limited quantity of the adsorbed Fe(CO)5 to the incident beam, and may also form a protective layer of the robust Fen(CO)m species during the initial stages of exposure to the electrons.

High Resolution Auger Depth Profiles Using a Dual Ion Gun System

1985 ◽  
Vol 54 ◽  
Author(s):  
S. Ingrey ◽  
J.P.D. Cook
Keyword(s):  
Electron Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Grazing Incidence ◽  
Low Energy ◽  
Multilayer Structures ◽  
Dramatic Decrease ◽  
Depth Profiles ◽  
Order Of Magnitude ◽  
Magnitude Improvement

A dual ion gun system has been proposed (D.E. Sykes et al, Appl. Surf. Sci. 5(1980)103) to reduce texturing and improve depth resolution during Auger sputter depth profiling. We have evaluated this ion gun configuration by profiling a variety of multilayer structures. With careful alignment of the guns, we have obtained a dramatic decrease in ion-induced texturing often seen when a single ion gun is used. This effect was particularly pronounced for polycrystalline Al films on Si where an order of magnitude improvement in depth resolution was achieved. Further refinements of the technique include the use of low energy (IkeV) grazing incidence xenon ions and a small electron beam probe area. Depth profiles obtained from Ni/Cr, W/Si, and GaAs/GaAlAs multilayer structures will also be discussed.

Semiconductor Failure Analysis Using EBIC and XFIB

2001 ◽  
Vol 7 (S2) ◽  
pp. 514-515 ◽  
Author(s):  
Larry Rice
Keyword(s):  
Electron Beam ◽  
Failure Analysis ◽  
Cross Sections ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Semiconductor Industry ◽  
Incident Beam ◽  
Yield Enhancement ◽  
Common Term ◽  
Electron Beam Induced Current

Electron beam induced current (EBIC) is the common term used in the semiconductor industry for the failure analysis and yield enhancement of semiconductor devices using SEM to electrically pinpoint leakage sites. EBIC is a useful technique for locating defects in diodes, transistors, and capacitors where the scanning electron microscope beam is used to generate a signal and the sample is the detector. Often during yield enhancement efforts the failure analyst is asked to determine the mechanism for which a PC structure (which may contain as many as a few hundred thousand structures in one device) is failing tests. Blind cross sections rarely give evidence of the failure mechanism. EBIC can be used to pinpoint the bad site which is then precision cross-sectioned using the focused ion beam (FIB).When an electron beam impinges on a semiconductor such as silicon, electron-hole pairs are created when the incident beam transfers enough energy to promote an electron from the valance band to the conduction band.

Irradiation Induced Effects in the Environmental Scanning Electron Microscope

1999 ◽  
Vol 5 (S2) ◽  
pp. 276-277
Author(s):  
Marion A. Stevens Kalceff
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Cross Sections ◽  
Diffusion Processes ◽  
High Sensitivity ◽  
Depth Resolution ◽  
Wide Band ◽  
Variable Pressure ◽  
Excess Charge ◽  
Pure Silicon

When a poorly conducting specimen is irradiated with an electron beam in a variable pressure electron microscope, the excess charge on the surface of the specimen can be neutralized by incident gas ions to prevent deflection and retarding of the electron beam. A small fraction (<10∼6) of the incident electrons are trapped at irradiation induced or pre-existing defects within the irradiated micro-volume of specimen. The trapped charge induces an electric field, which may result in the electro-migration and micro-segregation of charged mobile defect species within the irradiated volume of specimen. These charge induced effects are dependent on the density of trapping centers and their capture cross sections. In particular, evidence of these micro-diffusion processes can be directly observed in electron beam irradiated ultra pure silicon dioxide (SiO2) polymorphs using Cathodoluminescence (CL) microanalysis (spectroscopy and imaging). CL microanalysis enables both pre-existing and irradiation induced defects in wide band gap materials (i.e. semiconductors and insulators) to be monitored and characterized with high sensitivity and spatial resolution. Depth resolution is achieved by varying the electron beam energy.

Extracting Low Energy X-Ray Peaks From EDS and WDS Spectra

1998 ◽  
Vol 4 (S2) ◽  
pp. 218-219
Author(s):  
Robert L. Myklebust ◽  
Dale E. Newbury
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
High Performance ◽  
Incident Beam ◽  
Low Energy ◽  
Nanometer Scale ◽  
X Ray ◽  
Chemical Effects ◽  
Scanning Electron

Interest in electron beam x-ray microanalysis with low incident beam energies, defined arbitrarily as 5 keV and below, has been greatly stimulated in recent years by the development of the high performance field emission gun scanning electron microscope (FEG-SEM), which can produce a nanometer-scale probe with sufficient current to operate with both energy dispersive (EDS) and wavelength dispersive (WDS) spectrometers. Microanalysis in this regime requires the analyst to confront new spectrometry problems that are not typically encountered, or that can be safely ignored, when operating with conventional beam energies, 10 keV or greater. With low energy operation, the choice of atomic shells that can be accessed is restricted, forcing the analyst to make use of shells that have low fluorescence yields for intermediate and high atomic number elements, and possibly strong chemical effects, which are evident with high resolution x-ray spectrometry.

scholarly journals VUV Spectroscopy of Ar9+ and Kr9+ Low Energy Collision with H2

1988 ◽  
Vol 102 ◽  
pp. 365-368
Author(s):  
M. Druetta ◽  
T. Bouchama ◽  
S. Martin ◽  
J. Désesquelles
Keyword(s):  
Cross Sections ◽  
Ion Beam ◽  
Grazing Incidence ◽  
Ion Source ◽  
Low Energy ◽  
Absolute Calibration ◽  
Error Bar ◽  
Entrance Hole ◽  
Set Up ◽  
Beam Currents

Photon spectroscopy of low energy collisions between multicharged ions and neutrals has opened new possibilities of wavelength and energy level determination since recent multicharged ion sources like the E.C.R. source, giving μA electric current of highly multicharged ions, are available.The experimental set-up has been already described (1.2) The ion beam is produced by an E.C.R. ion source. Light emitted as a result of the collision is observed at 25* to the beam axis with a 3m grazing incidence (82*) spectrometer equipped with a 300 or 600 lines/mm grating blazed at 55.2 or 27.6 nm respectively. The detection is realised by micro-channel plates (MCP). Typical beam currents are 0.45 and 0.40 μA for Kr9+and Ar9+respectively, through the 8 mm diameter entrance hole of the gas cell. The gas pressure was kept at 5 × 10−5mbar. The emission cross sections of all the new observed lines have been mesured. Taking into account the statistics; the error on the beam intensity due to double collisions; the errors on the pressure, on the relative efficiency curve of the spectrometer and on the absolute calibration; we may estimate the error bar to ± 30%.

Investigate the nonuniformity of low-energy electron beam with large cross-sections

2012 ◽  
Vol 55 (4) ◽  
pp. 997-1000
Author(s):  
Jie Ren ◽  
JianMing Huang ◽  
YuTian Zhang ◽  
DeMing Li ◽  
NanKang Zhu
Keyword(s):  
Electron Beam ◽  
Cross Sections ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron

Slow-Scan CCD Observation of Backscattering Patterns in SEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1308-1309
Author(s):  
F. Ouyang ◽  
D. A. Ray ◽  
O. L. Krivanek
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Dynamic Range ◽  
High Sensitivity ◽  
Lens System ◽  
Wide Dynamic Range ◽  
Peltier Cooler ◽  
Diffraction Patterns ◽  
Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

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