I have GaN and AlN films ranging from 10 nm-150 nm in thickness. For the thicker films, I can use the general theta-2theta coupled scan. But for the thinner films, I have to use the grazing incidence geometry instead to compensate for the decreased thickness. Now the problem is that for all of my films GIXRD data are extremely noisy, to the point of being unusable. I keep the entrance angle 0.5 degree above the critical angle, and use a 2D detector to collect the signals. Generally speaking signal-to-noise ratio is supposed to be higher for thin films, when grazing incidence geometry is used. Any ideas?
When using GIXRD for thin films, your GIXRD pattern should not having noise because we are using GIXRD for thin film because grazing incidence only measure the thin film solely excluded the substrate. The grazing angle only detect the surface of thin film. Maybe something wrong with the set-up of GIXRD.
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