Substrate Effeci’s on the Surface Topography of Eva~~~d Gold Films - a Scanning Knelling Microscopy Investigation

Direct observation of surface roughness on metal films is a longstanding problem in thin film characte~tion. In this work the high quality of scanning tunnelhng microscopy (STM) was used for investigation of evaporated gold films. A scanning tunnel&g microscope able to scan areas up to 0.8 x 0.8 pm with high reproducibility is presented. The topography of 80 nm thick gold films grown under identical evaporation conditions was investigated as a function of the selected substrate material (Corning glass, silicon, NaCl, mica and highly oriented pyrolitic graphite (HOPG)). The incipient growth mechanism on the substrate is the primary reason for the surface roughness. Tbe real space images of the surface topography correlate very well with knowledge achieved from former growth experiments given in the literature. Moreover, very flat gold surfaces on HOPG allowed the observation of atomic corrugations in air environments.