Heteroepitaxial films of Ge1-xCx alloys (where x was less than 7%) were grown onto Si(100) substrates by using ultra-high vacuum chemical vapour deposition reactions involving GeH4 and (GeH3)4-xCHx (where x ranged from 1 to 3) at 470 to 540C. The layer composition and crystallinity were assessed by using Rutherford back-scattering spectroscopy (including C-resonance analysis), and the microstructure was characterized by using cross-sectional transmission electron microscopy. It was found that, regardless of the germylmethane precursor which was used for deposition, alloys with low C concentrations had a high crystallinity and a low defect density. Those with a high C content contained an increased density of structural defects. Greater C incorporation generally led to flatter and smoother surfaces; thus implying that the addition of C compensated strains due to lattice mismatch, and promoted 2-dimensional growth.

Structural Properties of Heteroepitaxial Germanium-Carbon Alloys Grown on Si(100). D.J.Smith, M.Todd, J.McMurran, J.Kouvetakis: Philosophical Magazine A, 2001, 81[6], 1613-24