Epitaxial growth of high-quality Ge films on nanostructured silicon substrates

Low (∼105cm−2) defect density, thick (∼10μm) epitaxially grown Ge films on nanostructured and planar silicon substrates using chemical vapor deposition are reported. The structural morphology of Ge films was evaluated using scanning electron microscopy, transmission electron microscopy, and high resolution x-ray diffraction measurements. The surface defect density was measured by counting etch pits. The growth quality of Ge films was significantly superior on nanostructured surfaces relative to the planar as demonstrated by (a) reduction in defect density from ∼6×108cm−2 for planar to ∼5×105cm−2, (b) reduction in Δω full width half maximum peaks of the reciprocal space maps of Ge epilayers from 373arcsec on planar (unpatterned) to 93arcsec on the nanostructured surfaces, and (c) the elimination of crosshatch pattern characteristic of planar surface growth.