Habib,
obviously your instrument is equipped with a not cooled solid state 1D
detector (maybe Bruker Lynxeye?) and a Ni filter what is used for
"selective" absorbtion of the Cu K beta radiation.
What you see in the pattern is mainly a significant part of the tube
emission spectrum, diffracted at the Si 111 plane, and modified by the
Ni K absorption edge.
The peak at ~ 25.8 ° is the remnant Si 111 diffracting the Cu Kbeta1
wavelength 1.39223 A.
The edge is the Ni K absorbtion edge (I don't know the wavelength of
the edge exactly, ~ 1.49 A), and the doublet at ~ 28.4 ° is the Si 111
diffracting the Cu K alpha1 and alpha2, 1.54059 and 1.54443 A,
respectively.
The asymmetric slope of the background on the rigth side of the peak
is the unfiltered part of the Bremsstrahlung, their low energy part
what is not more cut by the Ni absorbtion.
As your wafer is a perfect Si 111 plane you get extreme intensity and
< 1 % intensity effects become clearly visible. Maybe you have seen a
Si powder pattern what appeared to be "clean", but if you would have
measured the powder pattern with better counting statistics, your Si
111 region would look quite similar.
Greetings
Reinhard
Zitat von Habib Boughzala <habib.boughz...@ipein.rnu.tn>:
Dear all,
I would like to send you my witness related to this kind of observation.
I can assure that our Bruker D8 is clean and optimized!
In many cases of well conditioned thin film (spin coating or
controlled diffusion) material this kind of phenomenon is visible
around the highest reflection, especially when the preferred
orientation is drastically present.
So, in my opinion, Reinhard and Alan are right, and what is
observed is just like reflections broadening, asymmetry, shifting
...etc ... and can be related to the material behavior.
Now, what is the physical (crystallographic!) property responsible
of this phenomenon? let's open the floor for a large discussion.
Habib
--
TU Bergakademie Freiberg
Dr. R. Kleeberg
Mineralogisches Labor
Brennhausgasse 14
D-09596 Freiberg
Tel. ++49 (0) 3731-39-3244
Fax. ++49 (0) 3731-39-3129
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