Peculiarities in the Epitaxial Regrowth of Ion-Implanted Si1−xGex Alloy Layers Grown on Compositionally Graded Buffers

Abstract

AbstractSolid phase epitaxial regrowth of ion-implanted relaxed Si1-xGex layers was studied as a function of alloy composition (0.15< x <0.5) by a combination of Rutherford backscattering/ channeling spectrometry and transmission electron microscopy. The samples were grown by molecular beam epitaxy on compositionally graded buffers at different growth conditions. It was found that the regrowth velocity follows an Arrhenius curve in the investigated composition range and increases with increasing Ge content. The activation energies of the epitaxial regrowth were found to be higher than those expected from a linear interpolation between the values for pure Si and Ge. It is demonstrated that the regrowth velocities in the samples grown at 550 and 750°C and with low-rotational speed of the substrate during growth depend on the lateral position on the wafer and that they can be reduced by a preannealing treatment at high temperatures (σ920°C). We suggest that these effects arise from a compositional modulation in the alloy layer and, therefore, from a symmetrized strain, which can be reduced by a high temperature annealing.