Nucleation and surface reconstruction of Pd on Si(100) observed by scanning tunneling microscopy

Abstract

The initial stage of crystal growth in the Pd/Si(100) surface for coverages of less than 30 ML (monolayer) was investigated at annealing temperatures between 20°C and 1100°C using STM, LEED, AES and EELS. For deposition at room temperature, the growth mode is of the Volmer-Weber type and small clusters composed of a few atoms nucleate on the substrate Si dimer rows. As temperature increases, small clusters coalesce and these coalesced clusters have a 2 × 2 structure above 800°C. The c(4 × 2) and c(4 × 2) + c(4 × 6) structures appear above 900°C at 1 4 ML and are the same as those of the Pt/Si(100) surface. For coverages higher than 1 4 ML, excess Pd atoms form silicide (PdSi) islands on the superstructure surface in the Stranski-Krastanov mode. The electronic structure of the Pt/Si(100) surface depending on the coverage and annealing temperature is discussed from the AES and EELS data.