GexSi1-x layers are grown on Si substrates over the full range of alloy compositions at temperatures from 400-750°C by means of molecular beam epitaxy. At a given growth temperature films grow in a smooth, two-dimensional manner up to a critical germanium fraction xc. Beyond xc growth is rough. xc increases from 0.1 at 750°C to 1.0 at ∼550°C. Rutherford ion backscattering measurements indicate good crystallinity over a wide range of growth conditions. Transmission electron microscopy reveals that in thin films, the lattice mismatch between the GexSi1- x and Si layers can be accommodated by lattice distortion rather than by misfit dislocation formation. This pseudomorphic growth condition can persist to alloy thicknesses as large as l/4 μm.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)