Nucleation and growth of (10¯11) semi-polar AlN on (0001) AlN by Hydride Vapor Phase Epitaxy

Wurtzite AlN is widely used for deep ultraviolet optoelectronic devices (DUV), which are generally grown along the [0001]-direction of the wurtzite structure on currently available substrates. However, huge internal electrostatic fields are presented within the material along [0001] axis induced by piezoelectric and spontaneous polarization, which has limited the internal quantum efficiency of AlN based DUV LEDs dramatically. The internal fields can be strongly reduced by changing the epitaxial growth direction from the conventional polar c-direction into less polar crystal directions. Twinned crystal is a crystal consisting of two or more domains with the same crystal lattice and composition but different crystal orientations. In other words, twins can be induced to change crystal directions. In this work we demonstrated that the epitaxial growth of () semi-polar AlN on (0001) AlN by constructing () and () twin structures. This new method is relative feasible than conventional methods and it has huge prospect to develop high-quality semi-polar AlN.