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. D ue to the lattice parameters of Si, Ge, and C(diamond), the strained S i1-xGex layers can be strain compensated by the addition of substituti onal C. The epitaxial layers were fabricated at reduced pressure and t he reactive gases (silane, dichlorosilane, germane, and organometallic C-Si compound) were diluted in purified hydrogen. The growth temperat ures 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 40 00 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 pa rameters. Partial strain compensation was observed in layers thicker t han the critical thickness for Si1-xGex. These results are also compar ed to those of photoluminescence spectroscopy, where the observed misf it dislocation related bands (D1 and D2) are minimized in compensated samples.