We study the hardening effect by isoelectronic In doping on strain in GaN g
rown by metalorganic vapor phase epitaxy. Incorporated In into GaN was foun
d to pin the slip of screw dislocations, producing internal resistance stre
ss in GaN as a result of the hardening of GaN. We found that this result is
due to the interaction between In atoms and screw dislocations. The calcul
ated stress in GaN yielded by the interaction was found to be in good agree
ment with the measured stress by x-ray diffraction and Raman spectroscopy.
The internal resistance stress was estimated to be 0.3 GPa at maximum.