108 zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Surface Science 218 (1989) 108-126 North-Holland, Amsterdam zyxwvutsrq SUBSTRATE EFFECI’S ON THE SURFACE TOPOGRAPHY OF EVA~~~D GOLD FILMS - A SCANNING KNELLING MICROSCOPY INVESTIGATION zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONM J. VANCEA, G. REISS, F. SCHNEIDER, IL BA UER and H. HOFFMANN Institut zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA ftir Angewandte Physik, Universitiit Regensburg, Uniuersitiirsstrasse 31, D-8400 Regensburg, Fed. Rep. of Germany Received 23 November 1988; accepted for publication 16 March 1989 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. 1. Introduction The surface roughness has an import~t influence on the physical proper- ties of metal films as soon as the film thickness and surface roughness are of the same order of magnitude. Nevertheless, the evaluation of the surface roughness is up to now unsatisfactorily solved. For roughnesses larger than 8 nm, transmission electron microscopy (TEM) images of surface replicas were commonly employed [l-3]. Below this range only indirect methods were available in the past. The influence of the surface roughness on the thickness dependent resistiv- ity was introduced in 1970 by Namba [2]. Computer fitting of the model to the experimental curve gives the surface roughness as one of the fitting parame- ters. This method was extensively used in our former works [4-61 for a large number of polyc~st~~ne metal films (Au, Cu, Ag, Ni, Al, Pt). The surface roughness determined on this way ranged between 0.5 nm for Pt to lo-12 nm for Au and Ag and was strongly correlated with the growth mechanism of the respective metal on the glass substrate. The surface roughness therefore should ~39-6028/ 89/ $03.50 0 Elsevier Science Publishers B.V. (North-Holland Physics ~blis~ng Division)