Surface Polarity and Shape‐Controlled Synthesis of ZnO Nanostructures on GaN Thin Films Based on Catalyst‐Free Metalorganic Vapor Phase Epitaxy

Surface polarity and shape-controlled ZnO nanostructures are synthesized on GaN thin films using metalorganic vapor phase epitaxy (MOVPE). By adjusting the growth parameters from Zn-rich at low temperature to O-rich at high temperature, morphology of ZnO nanostructures was tuned from nonpolar, smooth-surfaced ZnO nanorod nanowall networks to O-polar, stacked pyramid-structured ZnO nanorods.