Gold films on silicon: Ion-bombardment-induced reactions between gold and silicon

Abstract

Thin gold films of thickness 80 and 25 nm deposited onto silicon were bombarded with 30 keV Ar + ions to fluences in the range from 4.8 × 10 18 to 1.6 × 10 21 ions m −2. Dynamic recoil mixing, i.e. controlled simultaneous deposition of gold and bombardment with Ar + ions, was carried out on gold films 30 nm thick on silicon. All the films were subsequently analysed by Rutherford backscattering spectroscopy, scanning electron microscopy and transmission electron microscopy. The results indicate the formation of a metastable amorphous phase with the composition Au 76Si 24. The formation of this phase is accompanied by the formation of surface ripples which develop into prominent islands on further ion bombardment. The amorphous phase is stable up to 413 K after which and up to a temperature of 613 K it turns into a stable large-grained polycrystalline compound with a similar composition, and this does not alter on subsequent cooling to room temperature.