Interface characterization of epitaxial Ag Films on Si(100) and Si(111) grown by molecular beam epitaxy

Abstract

Silver films grown on Si(100), Si(111), and thin oxide layers by molecular beam epitaxy (MBE) have been studied using multiple analysis techniques, including X-ray diffraction (pole-figure method and double-crystal diffractometry), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and MeV He⁺ Rutherford backscattering spectrometry (RBS)/ channeling. Despite the large lattice mismatch (∼25 pct) between Ag and Si, high-quality Ag single-crystal films (surface minimum yield χ_min = 6 to 10 pct) were grown on clean Si substrates. Ag(111) texture films were also grown on the oxide layers of Si(100) and Si(111) surfaces. The epitaxial Ag/Si interface was thermally stable up to at least 500 °C. The adhesion between Ag and the oxide layer was poor. The primary defects contained in the Ag/Si(111) were twins. The quantity of twinning depends on the film thickness and the substrate orientation. For both Ag/Si(100) and Ag/Si(111) epitaxial systems, a high-density defect region was contained in the Ag film within ∼1000 Å of the interface. Silver films grown on misoriented Si(111) substrates (∼4 deg off normal) were misoriented by 0. 5 deg toward the surface normal.