Radiative Auger study of transition-metal/silicon contacts

Silicon K-LL radiative Auger effect (RAE) spectra of annealed nickel/silicon and iron/silicon contacts together with that of a crystalline silicon were measured nondestructively using soft X-ray emission spectroscopy (SXES) apparatus. LL RAE spectra give us similar information to K-edge X-ray absorption spectra, i.e. unoccupied p-electron density of states (DOS), while the SXES give us the information on occupied valence band DOS. We demonstrate that the single apparatus without synchrotron radiation facility can give the information on both occupied and unoccupied electron states. Also we carried out the similar analysis of the oscillation in the RAE spectra to that of the extended X-ray absorption fine structure (EXAFS) to obtain inter-atomic lengths around a central atom. The result for annealed nickel/silicon was in good agreement with the crystal data of NiSi2. The RAE and SXES complement each other in the investigation of buried interface.