De-wetting of nanosized binary films: A case study on Au-Ge

Morphology of 7,5 nm thick polycrystalline Au-Ge layered film of a near eutectic composition has been studied in a wide temperature range by means of in situ TEM heating. It has been shown that de-wetting of the Au-Ge film on amorphous carbon substrate is activated at temperatures of about 150°C resulting in formation of large flatted islands with a mean thickness of 18 nm at pre-melting temperatures. An eutectic melting of the alloy film occurs at a temperature of 250°C inducing the conversion of flat islands to huge round-shaped binary particles. Correlation between coverage ratio and temperature of the film has been determined.