First stages of the Mo/Si(III) interface formation: An UPS, LEED and Auger study

Abstract

The behaviour of the Mo/Si(111) interface has been studied under atomically clean conditions using low-energy electron diffraction, UV photoemission and Auger spectroscopies. At room temperature, the Auger measurements indicate a layer-by-layer growth where no intermixing involving atomic motion across the interface occurs, in contrast with many transition-metal-silicon systems. The abrupt junction is confirmed by the UPS results which show a Mo adsorbed phase in the coverage range θ < 1 monolayer and a rapid recovering of the bulk Mo features for increasing θ. The band bending variation detected by the shift of the Si bulk structures on the UPS spectra shows that the Schottky barrier is formed before completion of the first Mo layer. These thin unreacted junctions are stable upon annealing up to 300°C. Above this temperature reactions take place and the MoSi2 silicide forms at ≈600°C.