Crystalline Phase Analysis by EELS and its Plasmon Signal
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The plasmon signal in EELS can provide information about the dielectric function [1], valence electron densities, and, in some cases, the phases presented in alloys.

Figure 3408a shows the comparison of EEL spectra between amorphous diamond and nanocrystalline diamond.

Comparison of EEL spectra between amorphous diamond and nanocrystalline diamond
Comparison of EEL spectra between amorphous diamond and nanocrystalline diamond
(a)
(b)

Figure 3408a. Comparisons of EELS plasmon (a) and core-loss in the energy range of 200 - 500 eV (a) between amorphous diamond and nanocrystalline diamond.

Figure 3408b shows the high-energy-resolution EELS spectra of plasmon region and core-loss in the energy region of 280 to 298 eV for C60 fullerene, and amorphous and crystalline diamond. Table 3408 lists the typical energy-loss peaks of the three forms of carbon.

Comparison of EEL spectra between amorphous diamond and nanocrystalline diamond
Comparison of EEL spectra between amorphous diamond and nanocrystalline diamond
(a)
(b)

Figure 3408b. High-energy-resolution EELS spectra of (a) plasmon region and (b) core-loss in the energy region of 280 to 298 eV for C60 fullerene, and amorphous and crystalline diamond.

Table 3408. Typical energy-loss peaks of the three forms of carbon.

Peaks
Transition
C60 fullerene
6.5 eV π → π*
285 eV 1s → π*
Amorphous diamond
31.5 eV σ plasmon
Crystalline diamond
34.0 eV σ plasmon

At micro-/nano-scales, EELS method often is the only efficient technique that can be used to determine the crystal phase in nanometer-sized area, for instance, for Ni silicide contacts in MOS structures. Therefore, if the EELS or plasmon signal is sensitive to the phase change of specific components, this technique should be the best choice.

 

 

 

 



 

 

 

 

 

 

 


[1] Buechner, U. The dielectric function of mica and quartz determined by electron energy losses, Journal of Physics C: Solid State Physics, 8, (1975) 2781-2787.

 

 

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