NUCLEATION AND SURFACE RECONSTRUCTION OF PD ON SI(100) OBSERVED BY SCANNING TUNNELING MICROSCOPY

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-degrees-C and 1100-degrees-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 x 2 structure above 800-degrees-C. The c(4 x 2) and c(4 x 2) + c(4 x 6) structures appear above 900-degrees-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 Pd/Si(100) surface depending on the coverage and annealing temperature is discussed from the