Say I have a sample, with the substrate as Si(111) and as-deposited thin film e.g. Au. The plane of interest is Au(111). I'll have to do the alignment since the sample is the single crystal. Then here comes the question, which plane I should use for the reference plane? The plane of Si(111), Au(111) or the physical film surface plane?

To elaborate the question, the alignment will decide which plane will be geometric flat (or say as tilt angle Chi=0 degree). If I don't do any tilting alignment, then the plane at Chi=0 is the sample surface. If I do the alignment in accordance to the Si(111) or Au(111) plane, then the sample may be tilted so that the Si(111) or Au(111) is now the starting point as Chi=0.

What difference in pole figure would I expect and which one should be done in favor of explaining the texture of the sample?

Thank you.