The thin-film formation of rhodium silicides

Abstract

The interaction of rhodium thin films with single‐crystal substrates of silicon leads to the formation of four silicides. RhSi forms by diffusion‐controlled kinetics at temperatures of about 350 °C with an activation energy of 1.9 eV. For long annealing times one observes the layered formation of Rh₂Si at the RhSi‐Rh interface. At higher temperatures, in the vicinity of 825 °C, Rh₄Si₅ forms in the same way as IrSi₃: it grows as islands with no measured composition gradient through the thickness of the films. Between 925 and 950 °C Rh₄Si₅ transforms to Rh₃Si₄. Oxidation experiments provide useful information about the stability of the Si‐rich phases, Rh₄Si₅ and Rh₃Si₄, and their mode of formation. The large number of silicides, four, formed in a single metal‐silicon system provides the opportunity to examine various modes of thin‐film interactions. Some striking differences in behavior in the otherwise similar systems, Ir‐Si and Rh‐Si, are briefly discussed.