Substrate effects on the surface topography of evaporated gold films—A scanning tunnelling microscopy investigation

Abstract

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.

Thermo-mechanical evolution of multilayer thin films: Part II. Microstructure evolution in Au/Cr/Si microcantilevers

“…That is, the {111} planes are parallel to the free surface, with random crystallographic orientation for the in-plane direction. This "{111} texture" has been observed for gold thin films grown on amorphous silicon dioxide [2], {0001} sapphire [3], {0001} highly oriented pyrolytic graphite [4], {0001} mica [5], {111} silicon [6], {111} NaCl [7,8], and {110} chromium [9,10]. The influence of surface energy increases as the thickness of the FCC metal film is decreased [1], resulting in very uniform {111} texture in ultra thin films.…”

“…The surface morphology of gold, grown at low homologous temperature, T h , is often reported to consist of the "rolling-hill" surface texture, which contains circular or squarish (rounded) nodules ranging in size from 50 to 100 nm in diameter [4,5,18,19]. For gold films deposited at a moderate or high T h , the free surface is seen to consist of the "terrace" structure [5].…”

“…The surface of gold may also be subject to evolution, for example, if deposited films are later annealed. Using scanning tunneling microscopy (STM), the free surface has been seen to evolve from the rolling hill into the terrace structure as the result of annealing [4,5,18,19].…”

The influence of surface roughness on electronic transport in thin films

“…The lm.oh~o af ~'hP th;n-fHm ~nrfaceq wa¢, t3er-formed with STM under amhent conditions [5] The materials have been Pt, Au, N~, Co and Cu. In order to evaluate possible influences of oxidation, Ni and Cu was partly covered with a 1-2 nm thick Au overlayer.…”

Morphological Investigations on Carbon-Black Particles by Atomic Force Microscopy

“…Our instrument is a variation of an earlier STM 8 and can be used as an AFM or a STM. The design of our atomic force microscope is sketched in Figure 1.…”