Evaporation of Epitaxial ZnO Films During Post-Deposition Annealing

概要

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The effect of evaporation on the surface morphology of $c$-oriented epitaxial ZnO (40 nm thick)/Al2O3(0001) films during post-deposition annealing was examined. On the basis of real-time synchrotron X-ray scattering analysis and atomic force microscopy (AFM), we found that evaporation as well as grain growth played important roles on the surface morphology of the ZnO/Al2O3(0001) films. Facets with higher surface energies than the (0001) planes were formed during grain growth in the initial stage of annealing. By the preferential evaporation of the prism planes, the surface morphology of the ZnO film eventually evolves into a two-dimensional (2D) flat (0001) surface at 800 °C, which was confirmed by AFM. The real-time measurement of film thickness during annealing clearly supports the previous results that evaporation is directly related to surface morphology. The evaporation rate is high in the initial stage, which is caused by the preferential evaporation from high-energy facets but decreases after the transition to a flat (0001) surface.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-06-15