Abstract
Reaction between deposited Ca layers and the Si(111) substrate has been studied by metastable-induced electron spectroscopy (MIES) and low-energy electron diffraction (LEED). When a Ca-deposited (about 1ML) Si(111) surface was annealed at temperatures in the range 470-570 K, the MIES spectrum showed a peak, named Ps, at a binding energy of about 7 eV which is assigned to be an isolated Si3s state. By referring electronic structure calculations for the bulk Ca-silicides, we confirmed that a solid-phase reaction at the Ca/Si interface to induce Ca2Si-like phases takes place at rather low annealing temperatures around 570 K. When Ca-covered (about 0.6 ML) Si(111) surfaces were annealed at temperatures in the range 770-870 K, the LEED showed 2× 1, 5× 1 and quasi-3× 2 reconstructions, depending on the temperature. We obtained MIES spectra from these surfaces involving spectral features which reflect local atomic structures of those Ca+Si surface phases. Correlations between the local atomic structure and the electronic structure probed by the MIES are discussed. [DOI: 10.1380/ejssnt.2007.89]
