Different growth modes of Au films on ZnO(0001¯)

The growth properties of gold films sputtered at room temperature (RT) and at 550 °C on O-terminated ZnO(0001¯)/Al2O3(112¯0) substrates were investigated by X-ray scattering, atomic force microscopy and by scanning electron microscopy. A maximal lattice mismatch of about 1.21% and 0.5% has been found in the growth direction for samples grown at 550 °C and RT, respectively. The chemical composition was determined by X-ray photoemission spectroscopy, which revealed a completely covered ZnO(0001¯) surface by Au after sputtering at RT. In addition, these measurements show that Au grows layer-by-layer at RT, but forms clusters if sputtered at 550 °C (Volmer-Weber growth mode).