Demonstration of laser-assisted epitaxial deposition of Ge _xSi_1-x alloys on single-crystal Si

We report initial results of a novel technique for epitaxial growth of Ge_xSi_1-x alloys on single-crystal Si. During electron beam deposition of amorphous Ge_xSi_1-x, an incident XeCl excimer laser, operating at 308 nm with a 30 ns pulse duration, melts and crystallizes the amorphous layer in situ after each ≊5 nm of deposition. This laser-induced melt extends approximately 20 nm and provides epitaxy from the underlying substrate (or previous layers) at each stage of deposition. This melt/solidification process can be repeated continuously until the final desired alloy thickness is achieved. For layers up to 260 nm with Ge concentrations of 1.5-3 at. %, MeV ion channeling and cross-sectional transmission electron microscopy confirm epitaxial growth.