Strain compensated heterostructures in the Si1−<i>x</i>−<i>y</i>Ge<i>x</i>C<i>y</i> ternary system

Abstract

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 °C, in order to have a reasonable growth rate and not form the stable SiC phase. The epitaxial layers, up to 4000 Å 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.