FORMATION OF ULTRATHIN NISI2 FILMS AND HETEROEPITAXIAL GROWTH OF EPI-NISI2/SI(111)

Abstract

Single-crystal NiSi2 layers of either type-A or type-B orientation were grown on a Si(111) substrate by solid-phase epitaxy. Epitaxial type-B NiSi2 was grown by deposition of Ni(<20 angstrom) on a Si(111)-7 x 7 surface at room temperature followed by in situ annealing at 650-degrees-C for 20 min. At a thickness of approximately 50 angstrom, a layered structure of type-B NiSi2(111)/type-A NiSi2(111)/Si(111) was formed. Pure type-A NiSi2 layer was grown by in situ annealing the Ni(200 angstrom)/Si(111)-7 x 7 sample at 750-degrees-C for 20 min. The minimum yields (chi(min)) of Ni in 2-MeV4 He+ ion backscattering spectrometry for the type-A and type-B NiSi2 were about 4 and 10%, respectively. The epitaxial orientations were mainly dependent on the Ni thickness and the annealing temperature.