Growth of pinhole-free epitaxial yttrium silicide on Si(111)

This paper reports the growth of pinhole-free epitaxial YSi2−x layers on Si(111) as thin as 30 Å. This has been accomplished by depositing both Y and Si at room temperature and then annealing to 500–900 °C. Use of the template method allows for the growth of thicker films also free of pinholes. Deposition of yttrium metal only onto Si(111) requires a temperature ∼300 °C for nucleation of the silicide reaction between the Y overlayer and Si substrate. Such a process creates small pinholes ∼500 Å in diameter, randomly distributed throughout the film. These pinholes increase in size with higher annealing temperature, resulting from a raised interface free energy intrinsic to the nucleation controlled growth.