Solid-phase epitaxy of CaSi 2 on Si(1 1 1) and the Schottky-barrier height of CaSi 2/Si(1 1 1)

Abstract

Thin Ca films were evaporated on Si(1 1 1) under UHV conditions and subsequently annealed in the temperature range 200–650 °C. The interdiffusion of Ca and Si was examined by ex situ Auger depth profiling. In situ monitoring of the Si 2p core-level shift by X-ray photoemission spectroscopy (XPS) was employed to study the silicide formation process. The formation temperature of CaSi 2 films on Si(1 1 1) was found to be about 350 °C. Epitaxial growth takes place at T≥400 °C. The morphology of the films, measured by atomic force microscopy (AFM), was correlated with their crystallinity as analyzed by X-ray diffraction (XRD). According to measurements of temperature-dependent I– V characteristics and internal photoemission the Schottky-barrier height of CaSi 2 on Si(1 1 1) amounts to qΦ Bn=0.25 eV on n-type and to qΦ Bp=0.82 eV on p-type silicon.