Characterization of ultrathin nickel layers on Si(111) using RHEED and RBS

Abstract

Ultrathin nickel layers (0–40 Å) on Si(111) were characterized using reflection high energy electron diffraction (RHEED) in conjunction with high-resolution Rutherford backscattering spectrometry (RBS). RBS shows that Ni, when deposited on Si(111) at 300 K, reacts with the Si to form clusters with an average composition close to Ni 2Si, until the clusters coalesce into a continuous layer. RHEED measurements show that the microstructure of this layer also matches the Ni 2Si composition: the film consists mainly of very fine-grained Ni 2Si crystallites (∼ 15 Å grain size) which are randomly oriented. Additional Ni deposition results in the accumulation of an unreacted fine-grained Ni layer on top of the silicide film.