Hello
Recently, I used four-circle thin film x-ray diffraction to characterize my sample, I have taken surface normal L-scan, off normal Phi scan, and in-plane radial scan.
In the L-scan, I found peaks appeared at the positions corresponding to Hexagonal Yttrium Aluminum Perovskite (0002) (0004) (0006) (0008). In the phi scan, I also found peaks appeared at H-YAP with 60-degree symmetry, thus, I said this is single crystal H-YAP. Moreover, in the L-scan and radial scan I have calculated the lattice constant a and c for the thin film to check whether the lattice strains exist or not.
Further more, I have calculated the coherence length of these peaks from Scherrer equation (4.5 nm), and used XRR to measure the thickness of the film (5.2 nm). The big difference between coherence length and the film thickness indicated that the crystallinity is not good, which is consistent with the bad rocking curve [H-YAP(0004), FWHM=0.24 degree]. And since no laue oscillation appeared at the side of peak, the interface between substrate and film will be rough.
Is there any other information I can get from the data?
Sorry I forgot to mention that my purpose is to grow H-YAP with good crystallinity on GaAs(111)A substrate.
I guess your L-Scan is a common theta/2theta so that you can see the different orders from the lattice plane parallel to the surface. This requires a quite ideal orientation since a tiny misalignment will change your peak profiles of the different orders since you (never) intersect the reciprocal space ideally. Moreover, you have to consider that the absorption is for every reflection different so that the virtual focus is in different depth. How much this will affect your lattice parameters I cannot tell you but I would not be surprized if there are small deviations for each 000l. However,since you assume lattice strain each 000l will be slightly shifted anyway. As you assume, your Phi-scan only shows your the "symmetry" of the single crystal. Here, different intensities can again tell you something about the misalignment of the sample normal compared to the phi-axis. All equivalent reflections should have exactly the same intensities! If they don't any further consclusions are at least questionable. How much Scherrer equation will give you reliable results I cannot say, especially since the difference between 4.4 and 5.2 appears to me not very big (because of possible misalignment errors). Moreover, you get only information about the thickness but not about the lateral crystal perfection. XRD is in that case perhaps not the best technique. The angular resolution is certainly hard to beat but this also has some drawback. Small misorientations will affect all of your profiles since you have then two or even more slightly misaligned reciprocal lattice which are convoluted by the detetion of the signal.
A 2D detector would be very helpful but from your explanations I assume that you are using a scintillator as detector, right? How big are your detector windows (horizontal and vertical slits)?
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