Characterization of two-dimensional Er-silicide / Si (111) interface

Abstract

Si2p core level photoemission as well as X-ray polarization dependent surface extended absorption fine structure (SEXAFS) have been used to characterize the interface of a twodimensional erbium silicide with Si(l1 l). This silicide, which consists of a hexagonal erbium monolayer located underneath a buckled Si top layer, was grown by deposition of one monolayer of erbium on clean Si(1 l l ) and annealing in the 400-6W°C temperature range. Photoemission experiments reveal a Schottky barrier height 6 as low as 0.13 rt 0.05 eV while for thicker erbium silicide layers Idg is found to be = 0.3 eV. SEXAFS measured at the Er L3 edge shows the location of erbium atoms in the eclipsed threefold hollow sites of the Si substrate.The average distance of erbium to the silicon of the substrate is found to be 3.10 * 0.04 A, whereas the distance of erbium atoms to their three first neighbors in the Si top layer is found to be 2.94 k 0.04 A.