The structure of a (1¯2•0) prismatic stacking fault was calculated from first principles. The fault vector was ½[10•1]. Such a fault was believed to occur when GaN was grown onto sapphire or SiC, and was thought to originate when basal-plane stacking faults folded onto the prism plane. It was found that that the boundary was heavily reconstructed, but that the atoms remained 4-fold coordinated, with no wrong bonds or dangling bonds present. In spite of the existence of distorted 4-membered rings of bonds at the boundary, the fault did not introduce deep states into the gap. The calculated stacking fault energy was 0.072eV/Å2.

J.E.Northrup: Applied Physics Letters, 1998, 72[18], 2316-8