Right now I'm investigating thin NiOx deposited by hollow cathode gas flow sputtering. To accuratly check for the influence of p(O2) on lattice parameters i decided to work with TOPAS (Bruker).
The films are 80 nm NiO on Corning Eagle XG.
My measurements are carry out on a Bruker D8 Discover with cupper-cathode in GID geometry at incident angle of 1°: goniometer radius=430mm, PSD-window=1.9119°. On primary side a Göbel-Mirror and a 0,2 mm Slit are mounted on the secondary side only a parallel plate collimator (Equa. Soller 0.4°).
My question now: How does my emssion line profile must look? (since I use a goeble mirror it cuts kB, and parts of ka2 and also distorts with angle) I could find accurate values, or suggestions on this.
And how to simulate the fixed Omega (incident angle)? I do not use zero-correction or hight offset, since I'm in GID.
2 Phases is accurate i guess: one for SiO2 (Substrate) and one for my film. The Cubic lattice is not able to recreate all peak positions. Therefore I use rhom. NiO (ICDD 00-044-1159)
Please have a look on the attched files.
Thanks in advance!
This answer is a guess, I have not worked with these for 20 years now.
When you have a thin film, if the thin film is thicker than 1 micron, you can not see the substrate in the XRD. Oxygen has a very high peak at 2*theta = 34.5 degrees in the XRD, thus the higher and sharper this O peak the better the crystalinity (and the O content) of the NiO. I could be mistaking though, I was working with ZnO. (search for the XRD of NiO on researchgate and for the Oxygen line)
If I get it right the macro you are using to model the instrumental profile should only be used for Bragg-Brentano geometry. Either try to use an instrumental standard for your setup (and model the broadening empirically) or consult topas specific forums to check out whether somebody has applied the fundamental parameters approach for a Göbel mirror. I regard this as likely....
Thanks for your answers so far!
Mr. Leineweber, i considered your empirical way of modelling the instrumental function by measuring against a corundum standard in the same setup. From this I was able to find the instrumental contribution modeled with a Lorentzian and Gaussian convolution.
With this function, I was able to fit the cubic NiO Phase to the measurements.
A reported shift in Cu Ka2 due to the Mirror is not observed in our setup. Atleast within the measured range.
I had the chance to talk to a Bruker Scientist, and he recommended me the same procedure.
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