Strained solid phase epitaxial (SPE) regrowth of amorphous GexSi1-x on Si (100) substrates was studied using time-resolved reflectivity
(TRR). Films of CVD-grown Ge0.13Si0.87 on Si were
amorphized by Si ion implantation, and subsequently regrown at temperatures
between 550°C and 610°. Information on regrowth dynamics and interface
roughness evolution was obtained by accurately modeling the complicated TRR
data for GexSi1-x regrowth using a Moving, statistically roughening interface. The SPE
regrowth rate slowed as the interface crossed into the GexSi1-x layer and the originally planar interface roughened, as confirmed by
transmission electron Microscopy. A Minimum in the regrowth velocity was
observed after regrowing approximately 60 nm into the GexSi1-x layer; the SPE rate subsequently increased to a final,
thickness-dependent velocity that was still below that for pure Si. Upon
entering the GexSi1-x layer, the interface roughened quickly to a 15–20 nm amplitude,
increasing only slightly more during the remainder of regrowth. The degree
of roughening and velocity reduction was found to be dependent on the anneal
temperature. In contrast, samples with low Ge concentrations (< 3 at.%)
prepared by ion implantation exhibited minimal interface roughening and
essentially identical SPE velocities as pure Si.