Mitigating solid-state dewetting via abnormal grain growth under epitaxial conditions

The influence of temperature on the thermal stability of Au thin films on polar Zn-ZnO(0001) substrates is systematically investigated via correlative scanning electron microscopy methods. While solid-state dewetting leads to thin film degradation at elevated temperatures, a processing window including rapid thermal annealing processes around 800 °C is identified in which abnormal grain growth stabilizes the thin film against dewetting. Here, we identify the mazed bicrystalline structure solely consisting of low-energy grain boundaries as a stabilizing factor. It is demonstrated that the resulting structure i) exhibits a high stability against dewetting during subsequent heat treatments and ii) can be used to fabricate large triangular and highly oriented Au structures via a two-step annealing process. The contribution highlights the competition between grain growth under epitaxial conditions and dewetting including the role of fast versus slow heating ramps and their impact on the resulting thin film properties.