Ultrathin film growth of silicides studied using microprobe reflection high-energy electron diffraction and Auger

The generic parameters and processes involved in solid phase epitaxial growth of ultrathin films by contact reaction are discussed. The particular strengths of quantitative reflection high-energy electron diffraction (RHEED) and Auger line-shape analyses for separating coexisting phases are demonstrated with examples from the Ni/Si (111) system. Using RHEED Kikuchi patterns and rocking curves, we identify the ordered structures NiSi2 (mixed A and B type) and Ni2Si-0. From the Auger line shape we find that the low-coverage room-temperature material is disordered Ni2Si, the NiSi2 epitaxial layers are capped with a layer of excess silicon, and the surface layers pass through a NiSi like phase in the transformation from Ni2Si to NiSi2.