Electron Energy Loss Spectrometry in the Electron Microscope

Author(s):  
L. M. Brown
Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.


1992 ◽  
Vol 259 ◽  
Author(s):  
Selmer S. Wong ◽  
Shouleh Nikzad ◽  
Channing C. Ahn ◽  
Aimee L. Smith ◽  
Harry A. Atwater

ABSTRACTWe have employed reflection electron energy loss spectrometry (REELS), a surface chemical analysis technique, in order to analyze contaminant coverages at the submonolayer level during low-temperature in situ cleaning of hydrogen-terminated Si(100). The chemical composition of the surface was analyzed by measurements of the C K, O K and Si L2,3 core loss intensities at various stages of the cleaning. These results were quantified using SiC(100) and SiO2 as reference standards for C and O coverage. Room temperature REELS core loss intensity analysis after sample insertion reveals carbon at fractional monolayer coverage. We have established the REELS detection limit for carbon coverage to be 5±2% of a monolayer. A study of temperature-dependent hydrocarbon desorption from hydrogen-terminated Si(100) reveals the absence of carbon on the surface at temperatures greater than 200°C. This indicates the feasibility of epitaxial growth following an in situ low-temperature cleaning and also indicates the power of REELS as an in situ technique for assessment of surface cleanliness.


Author(s):  
M Stöger-Pollach ◽  
C Hébert ◽  
E C Karl-Rückert ◽  
P Schattschneider ◽  
B Rau ◽  
...  

1999 ◽  
Vol 5 (S2) ◽  
pp. 620-621
Author(s):  
K.T. Moore ◽  
J.M. Howe

The dependence of diffraction contrast on electron energy loss is an important relationship that needs to be understood because of its potential effect on energy-filtering transmission electron microscope (EFTEM) images. Often when either a two-window jump-ratio image or a three-window elemental map is produced diffraction contrast is not totally eliminated and contributes to the intensity of the final EFTEM image. Background removal procedures often are unable to completely account for intensity changes due to dynamical effects (i.e., elastic scattering) that occur between images acquired at different energy losses, leaving artifacts in the final EFTEM image.In this study, the relationship between diffraction contrast and electron energy loss was investigated by obtaining EFTEM images of a bend contour in aluminum in 100 eV increments from 0 to 1000 eV (Fig. 1). EFTEM images were acquired a JOEL 2010F FEG TEM with a Gatan imaging filter (GIF) at a microscope magnification of 8 kX using a 1 eV/pixel dispersion, 2X binning (512 x 512) and exposure times ranging from 0.25 s for 0 eV energy loss up to 132 sec for 1000 eV energy loss.


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