Zinc oxide (ZnO) as an extremely bright ultraviolet emitter is an attractive material for photonic devices. In this work photonic resonators and nanostructures with charge carrier localization on the basis of ZnO heterosystems have been created. As in the ZnO system selective etching processes, which are essential for the fabrication of devices, are difficult to achieve, ZnO layers were grown on pre-patterned silicon (Si) and silicon dioxide (SiO2) substrates. Additionally, those bring along the advantage of the integrability into existing circuits, which are often based on silicon. However, the large differences in lattice constants and thermal expansion coefficients lead to polycrystalline layers of small grains. Nevertheless, ZnO layers grown by plasma assisted molecular beam epitaxy exhibit high homogeneity and low surface roughness. By thermal annealing the electronic and structural qualities of the ZnO layers have been significantly improved due to the merging of the individual grains. Thus, the grain rotation induced coalescence could be demonstrated in three dimensions for the first time. Using a diffusive model, the recrystallization was described on a kinetic time scale and a corresponding mobility parameter has been determined. Compared to parameters in two dimensions, the coalescence in 3D is much faster due to the additional degree of freedom of the twist- and tilt-rotation. Carrier localization in ZnO quantumwires has been achieved by the overgrowth of crystallographically etched V-grooves with Si(111) side walls inside a Si(100) sample. Whereas high quality photonic microdisk and photonic crystal resonators have been realized by the overgrowth of pre-structured SiO2 geometries, which were released via chemical undercutting.