Formation of the PtSi(111) interface

We have studied the atomic structure and some of the electronic properties of the PtSi(111) interface as it forms under evaporation of Pt onto a clean silicon surface near room temperature, using Auger electron spectroscopy (AES), photoemission with synchrotron radiation, low energy electron diffraction (LEED), and Auger/sputter profiling. Growth of a single homogeneous Pt monolayer is observed at sufficiently low rates of deposition of Pt. For Pt coverages above one monolayer a reaction occurs between Pt and Si resulting in silicide-like features in the Si(L23VV) Auger spectrum and in valence band and core level photoemission excited with synchrotron radiation. An inward diffusion of Pt is observed in cases of elevated substrate temperatures and during ion bombardment. For slow deposition of Pt on a 7 × 7 surface, a change of the 7 × 7 pattern into a weak √3 × √3 pattern is observed. Further experiments were conducted to investigate the annealing behaviour of monolayer deposits with LEED and AES. With annealing to ∼ 800°C sharp √3 × √3 patterns are found. At intermediate annealing temperatures (320°C). a √7 × √7 pattern is sometimes observed.