GROWTH MODE OF ULTRATHIN SB LAYERS ON SI STUDIED BY SPECTROSCOPIC ELLIPSOMETRY AND RAMAN-SCATTERING

The growth of Sb layers on Si(100), -(110) and -(111) surfaces was studied by spectroscopic ellipsometry (SE) and Raman scattering (RS). The vibrational Raman spectra show that at room temperature Sb grows first in an amorphous structure but then crystallises in the rombohedral bulk structure D3d. This phase transition is also seen for coverages beyond 15 nm in the dielectric function of the Sb layer obtained by ellipsometry in the range 1.8 to 5.5 eV. The E2 gap structure of Sb becomes more pronounce after crystallisation and the imaginary part of the dielectric function reflects metallic behaviour. This development continues with further deposition of Sb until at approximately 40 nm coverage the bulk dielectric function is reached. In contrast to Sb on (110) surfaces of III-V semiconductors, however, no evidence for the formation of a stable epitaxial monolayer of Sb on Si is found. This is also distinct to As on Si, where an ordered first monolayer has been observed for all three surface orientations.