STRAIN COMPENSATED HETEROSTRUCTURES IN THE SI1-X-YGEXCY TERNARY-SYSTEM

Si1-x-yGexCy pseudomorphic heterostructures have been grown on Si(100) substrates using a rapid thermal chemical vapor deposition reactor. Due to the lattice parameters of Si, Ge, and C(diamond), the strained Si1-xGex layers can be strain compensated by the addition of substitutional C. The epitaxial layers were fabricated at reduced pressure and the reactive gases (silane, dichlorosilane, germane, and organometallic C-Si compound) were diluted in purified hydrogen. The growth temperatures were 650 and 550-degrees-C, in order to have a reasonable growth rate and not form the stable SiC phase. The epitaxial layers, up to 4000 angstrom in thickness and x = 20%, were compensated by up to 1% of substitutional C as measured by infrared spectroscopy at 605 cm-1. The lattice parameters were measured by x-ray diffraction using the [004] and [224] substrate difraction peaks to directly obtain the strain parameters. Partial strain compensation was observed in layers thicker than the critical thickness for Si1-xGex. These results are also compared to those of photoluminescence spectroscopy, where the observed misfit dislocation related bands (D1 and D2) are minimized in compensated samples.