Initial stages of diffusion and phase formation in Sc/Si layered systems

Abstract

Kinetics of phase formation Sc/Si multilayers and Si/Sc/Si three-layers within the temperature range of 130-400°C has been studied by cross-sectional transmission electron microscopy and small-angle X-ray reflectometry. Growth of ScSi silicide governed by diffusion kinetics was observed at all temperatures. Two growth stages of nonparabolic and parabolic behavior were revealed. Initial nonparabolic stage is characterized by higher diffusion coefficient, which decreases during annealing in 20 times due to silicide structural relaxation. After annihilation of excess free volume a transition to parabolic growth takes place. Parameters of interdiffusion (activation energy E ≈1 eV and pre-exponential factor D₀ = 4.10⁻¹² m²s⁻¹) were determined for parabolic growth stage.