XRD FWHM, debye-scherrer's formula & AFM surface morphology

[jcli0002]

Hi guys,
I have an question about the correlation between grain size caculated from debye-scherrer and the AFM results for my AlN epi layer samples.

From my AFM results, the trend of grain size of three samples are getting smaller( around 200-10 nm range among three samples). but the FWHM of XRD from the samples are 0.24,0.22,
0.21 degree. according to the scherrer's formula, the grain size should increase and get bigger.
it seems it contradict the AFM results.

I am wondering whether it is proper correlation between AFM results and the calculation from scherrer's formula.

THanks

J.C.

 

[samira_63]

Hi
I want to know, in scherre equation, the FWHM should be in gradian or degree?