On the origin of the (1216)-orientation in epitaxial AIN layers on R-plane sapphire

Epitaxial AIN grown by MOCVD on (011 2)Al₂O₃ substrates usually is (12 10)-oriented. Here for the first time (12 16)AIN was found in MOCVD layers. This AIN orientation is known from other growth techniques, its origin is generally not understood. An explanation is given based on twinning in the early growth stages which is also applicable to the growth of (12 16)ZnO on (011 2)Al₂O₃.