Three-dimensionally-architectured GaN light emitting crystals
We demonstrate the epitaxial growth of three-dimensional (3D) GaN single crystal arrays through metal–organic vapor phase epitaxy (MOVPE) on lattice-matched ZnO templates that were achieved via hydrothermal growth in which we controlled the position, size and morphology of the layer. To prevent collapse of the crystals during MOVPE growth, graphene sheets were employed as a protection/mask layer, and initial GaN growth was performed at a relatively low temperature under hydrogen-depleted conditions. Temperature-dependent growth behaviors of GaN crystals on diverse types of ZnO templates can facilitate the control of hexagonal crystal shapes including pencil, tent and plate shapes. Furthermore, a 3D light emitting crystal array was demonstrated through subsequent growth of high-quality n-type and p-type GaN layers.