Si1−x−yGexCy alloy growth by electron cyclotron resonance plasma-assisted Si molecular beam epitaxy

We report the growth of Si1−yCy and Si1−x−yGexCy alloys by electron cyclotron resonance (ECR) plasma-assisted Si MBE using an argon/methane gas mixture. No significant carbon incorporation was measured in films grown under a high methane partial pressure without plasma excitation, whereas C incorporation up to ≈2 at.% has been achieved upon plasma excitation. Various Si/Si1−yCy and Si/Si1−x−yGexCy multilayers have been grown and characterized. The structures show good structural properties and sharp interfaces, with carbon being essentially substitutionally incorporated up to concentrations of ≈1%. Raman scattering spectroscopy of Si1−yCy revealed two bands near 480 and 606 cm−1 that are indicative of substitutional incorporation. Strong strain compensation and enhanced thermal stability were observed in Si1−x−yGexCy alloys. These results suggest that ECR plasma-assisted Si MBE may be an interesting alternative to more conventional methods for producing lattice matched epitaxial Si1−yCy and Si1−x−yGexCy thin films on Si.