Impacts of off-angle and off-direction on surface morphology of GaN grown by metalorganic vapor phase epitaxy on (0001) GaN substrate.

• The macroscopic morphology changes depending on the off-angle and its direction. • Macrostep and hillock form growth is observed below a certain off angle. • The lowest off-angle at which smooth morphology can be obtained is direction-dependent. • The m -direction provide the lowest off-angle and the step flow growth. • The off-angle and off-directions are important factors for morphologies control. [ABSTRACT FROM AUTHOR]