Vacuum-ultraviolet reflectance difference spectroscopy for characterizing dielectrics-semiconductor interfaces

Reflectance difference spectroscopy (RDS) was applied to the characterization of SiO2/Si, GeO2/Ge, and high-k/III-V interface structures. We extended the spectral range of RDS to 8.4 eV in order to explore the optical transitions at the dielectrics-semiconductor interfaces as well as to have a high sensitivity to the interface anisotropy. Si surfaces with (110), (113), (331) and (120) orientations showed oxidation-induced RD changes in the vacuum-ultraviolet (VUV) range which were dependent on the surface orientation, oxidation method (dry or wet), and oxidation temperature. The Ge(110) surface also showed characteristic oxidation-induced changes in the VUV range, whereas Al2O3 deposition on GaAs(001) and InP(001) surfaces induced only the RD amplitude changes.