Figure 3
From: Nucleation and growth of (10͞11) semi-polar AlN on (0001) AlN by Hydride Vapor Phase Epitaxy

ECS model.
(a) When the growth temperature is high enough, AlN grows along [0001] direction and (0001) is the facet on surface. (b) Other facet on surface instead of (0001) occurs while the growth temperature decreases. (c) () plane becomes facet on surface when the growth temperature is lower than 1390 °C. (d) (
) twin boundaries formed at the basis of (
) facets on surface.