Molecular beam epitaxial growth and photoluminescence investigation of Si 1− yC y layers

Abstract

We studied the substitutional carbon incorporation in Si 1− y C y layers grown by molecular beam epitaxy (MBE) on Si(100). We grew a series of pseudomorphic Si 1− y C y /Si superlattices (SL) with carbon concentrations between 0 and 2% and growth temperatures varying between 400 and 650°C. From a comparison between measured and simulated X-ray rocking curves of our samples, we determined the substitutional carbon content as a function of the growth temperature. We observed a decrease of the substitutional carbon incorporation with increasing growth temperature and increasing carbon flux. Reflection high energy electron diffraction (RHEED) showed a 3D pattern of those layers, which had not incorporated all the offered C atoms substitutionally. This result is confirmed by atomic force microscopy investigations of Si 1− y C y epilayers grown at different temperatures. To check the crystal quality we performed photoluminescence (PL) investigations of a Si/Si 1− y C y SL and of a 1100 Å Si 0.99C 0.01 epilayer. Before and after annealing the epilayer was analyzed by PL and X-ray diffraction. We observed a blueshift of the NP and TO line, which is caused by a homogenization of potential fluctuations in the band edge energies.