Investigation of the Ti/MgCl2 interface on a Si(111) 7 × 7 substrate

摘要

Photoelectron spectroscopy with synchrotron radiation, low energy electron diffraction, and ionscattering spectroscopy were used in order to study the Ti/MgCl2 interface grown on an atomically clean Si(111) 7 × 7 substrate. A series of high resolution spectra after deposition of a thick MgCl2 layer, step by step deposition of Ti and gradual annealing, indicated a very reactive interface even at room temperature. Strong interaction between the incoming Ti atoms and the MgCl2 layer, leads to the formation of Ti2+ and Ti4+ oxidation states. The interfacial interaction continues even at multilayer Ti coverage mainly by the partial disruption of Mg-Cl bonds and the formation of Ti-Cl sites, rendering this interface a very promising UHV-compatible model of a pre-catalyst for olefin polymerization. After the final annealing, the MgCl2 multilayers desorb while Ti remains on the surface forming a silicide layer on which Cl and Mg atoms are attached.