High Energy Ion Bombardment of Thin Films: From Platinum on Silicon to Platinum Silicide

Abstract

The effect of high energy ion bombardment on ultra-thin Pt films deposited on silicon substrates was investigated. The changes caused by the bombardment were studied using a combined characterization approach, consisting of X-Ray Photoelectron Spectroscopy (XPS) and electrochemical measurements. The chemical sensitivity of XPS helped determine locally the nature of the film after bombardment, which transitions to platinum silicide, as demonstrated by a dramatic evolution of the Pt4f and valence band spectra. Cyclic voltammetry provided the average electrochemical response of the entire sample surface (1 cm 2 ) in contact with an acidic solution. This technique is particularly sensitive to the evolution of the platinum undergoing bombardment. Initially showing a typical Pt electrochemical response, the film undergoes an irreversible transformation, leading to the absence of any metallic platinum on the surface after a sufficient bombardment dose, based on the absence of electrocatalytic activity. This study highlights the complementarity of XPS and electrochemical characterization. The platinum silicide fabrication technique described here may also be of interest for electronics applications, since platinum silicide contacts are used in a variety of thin film devices.

Ionic Bombardment to Tune the Electrochemical Properties of a Semiconductor

“…In this work, we aim to improve the evaluation of ion-surface interactions on a model system, Indium Phosphide, for which optoelectronic properties are very sensitive to any modification. Previous tests have been performed on platinum films covering silicon substrates (11,12). The use of solid/liquid electrochemical interfaces response is really efficient and quantitative to provide relevant information on the modification made (metallization, amorphization preferential sputtering, disorder).…”