Orientation control of GaN { 1 1 2 ¯ 2 } and { 1 0 1 ¯ 3 ¯ } grown on ( 1 0 1 ¯ 0 ) sapphire by metal-organic vapor phase epitaxy

The growth of semipolar GaN on ( 1 0 1 ¯ 0 ) (m-plane) sapphire was investigated by metal-organic vapor phase epitaxy (MOVPE). Most of the layers were polycrystalline with { 1 1 2 ¯ 2 } , { 1 0 1 ¯ 3 ¯ } and { 1 0 1 ¯ 0 } as the dominant surface orientations. For incomplete nitridation and recrystallization the { 1 0 1 ¯ 3 ¯ } orientation was dominant. However, the { 1 0 1 ¯ 3 ¯ } surface is rough due to twinned crystallites. Growth at lower temperatures and with reduced gas flow velocity results in predominantly { 1 1 2 ¯ 2 } oriented smooth layers. The orientation was also found to be influenced by the nitridation and recrystallization process.