Strain relaxation of epitaxial SiGe layers on Si(100) improved by hydrogenimplantation

We propose a new method to fabricate strain relaxed high quality Si1-xGex l ayers on Si by hydrogen implantation and thermal annealing. Hydrogen implan tation is used to form a narrow defect band slightly below the SiGe/Si inte rface, During subsequent annealing hydrogen platelets and cavities form, gi ving rise to strongly enhanced strain relaxation in the SiGe epilayer. As c ompared to thermally induced strain relaxed Si-Ge epilayers, the hydrogen i mplanted and annealed samples show a greatly reduced threading dislocation density and a much higher degree of strain relaxation (90%). We assume that the hydrogen induced defect band promotes strain relaxation via preferred nucleation of dislocation loops in the defect band which extend to the inte rface to form misfit segments. The samples have been investigated by X-ray diffraction, Rutherford backscattering spectrometry and transmission electr on microscopy, (C) 1999 Elsevier Science B.V. All rights reserved.