Ge<i>x</i>Si1−<i>x</i>/Si strained-layer superlattice grown by molecular beam epitaxy

TLDR

GexSi1−x films are grown on Si by molecular beam epitaxy and assembled into strained‑layer superlattices, characterized by optical, ion‑scattering, diffraction, and TEM techniques. All alloy compositions grow smoothly on silicon, and for x≤0.5 dislocation‑free films are achievable by strained‑layer epitaxy, with critical thickness and composition limits quantified.

Abstract

GexSi1−x films are grown on Si by molecular beam epitaxy and analyzed by Nomarski optical interference microscopy, Rutherford ion backscattering and channeling, x-ray diffraction, and transmission electron microscopy. The full range of alloy compositions will grow smoothly on silicon. GexSi1−x films with x≤0.5 can be grown free of dislocations by means of strained-layer epitaxy where lattice mismatch is accommodated by tetragonal strain. Critical thickness and composition values are tabulated for strained-layer growth. Multiple strained layers are combined to form a GexSi1−x/Si strained-layer superlattice.