Nucleation and growth modes of ZnO deposited on 6H-SiC substrates

ZnO nucleated initially with two-dimensional (2D) islands on 6H-SiC substrates. With the increase of ZnO layer thickness, however, the 2D islands led to coalescence and grain growths. The aspect ratios of these islands/coalescences/grains were found to be thickness dependence that has been interpreted by a schematic model. The growth mode transition from 2D islands to three-dimensional (3D) grains is the result of strain energy relaxation accumulated by lattice and thermal mismatches. An analog result diffracted in transmission electron microscopy with misfit dislocations that extended into the ZnO epilayers to be ≤150 nm. The secondary ion-mass spectroscopy analysis exhibited anomalous impurities contributed by an interdiffusion in between ZnO and SiC materials.