Stress and interface morphology contributions in the crystallization kinetics of a GexSi1-x thin layer on (100)Si

A study of the solid phase epitaxial growth from amorphous phase of a strained GexSi1-x thin layer made by Ge-74(+) ion implantation of (100) Si is presented. Ge peak concentration is 6.4 at. %. Principally employed techniques are time-resolved reflectivity for crystallization rate measurements and cross sectional transmission electron microscopy (TEM) for interface morphology imaging. The kinetics is heavily affected by the mismatch stress induced by the Ge; the experimental data cannot however be explained considering only the average stress along the amorphous-crystal interface and another mechanism is required. Cross sectional TEM observations of partially crystallized samples reveal the tendency of the interface to roughen with an evolution reflected in the crystallization activation energy Such roughness is assumed to affect the kinetics by locally enhancing the interface stress.