Hi everyone. Recently, I did (002) XRD scanning to get the rocking curve of a sample of GaN. From the measurement, I found that the FWHM of the sample is ~1.35 degree. I tried to convert it into radian unit using this formula: angle in radian=angle in degree x π /180 (degree). I got the answer around 4.74 radian. Then I used this value to estimate the screw dislocation density of the sample using this formula; screw dislocation density = FWHM2/4.35 x burger vector (0.5185). The answer is far off the reasonable value that typically reported for GaN. Could anyone help me?