Growth of thin, flat, epitaxial (1 1 1) oriented gold films on c-cut sapphire

A new growth procedure has been developed to prepare thin (<50 nm), flat (roughness ∼0.3–1 nmrms), epitaxial Au films on top of an insulating substrate without using a magnetic seedlayer. This could be obtained by depositing first a Nb seedlayer (⩽1 nm) at room temperature on top of c-cut sapphire followed by evaporating Au at a rate of 0.05–0.1 nm/s at 300 °C. This procedure resulted in (1 1 1) oriented flat Au films even for thickness well below 50 nm. The flatness of these films was consistently confirmed by atomic force and scanning tunneling microscopy, their excellent epitaxial quality (rocking width 0.1°–0.3°) by X-ray diffractometry and reflected high energy electron diffraction.