Ion induced segregation in gold nanostructured thin films on silicon

TL;DR

This study demonstrates how high-energy gold ion irradiation causes gold atoms in nanostructures on silicon to migrate, form silicides, and segregate to surfaces, revealing ion-induced atomic redistribution mechanisms.

Contribution

It provides direct observations of gold atom segregation and silicide formation in nanostructured films under ion irradiation, highlighting the effects of fluence on atomic transport.

Findings

Gold atoms migrate up to 60 nm into silicon substrate.

Formation of gold silicide occurs at lower fluences.

High fluence causes gold segregation to defect-rich surfaces.

Abstract

We report a direct observation of segregation of gold atoms to the near surface regime due to 1.5 MeV Au2+ ion impact on isolated gold nanostructures deposited on silicon. Irradiation at fluences of 6x10^13, 1x10^14 and 5x10^14 ions cm-2 at a high beam flux of 6.3x1012 ions cm-2 s-1 show a maximum transported distance of gold atoms into the silicon substrate to be 60, 45 and 23 nm, respectively. At a lower fluence (6x1013 ions cm-2) transport has been found to be associated with the formation of gold silicide (Au5Si2). At a high fluence value of 5x10^14 ions cm-2, disassociation of gold silicide and out-diffusion lead to segregation of gold to defect - rich surface and interface region.