Epitaxial GexSi1−x/Si (100) structures produced by pulsed laser mixing of evaporated Ge on Si (100) substrates

Publisher Website
Google Scholar
Abstract
Heteroepitaxial GexSi1−x alloy layers have been formed by pulsed laser induced mixing of pure germanium films and Si (100) substrates. Ge films 50–200 Å thick are electron beam evaporated onto Si (100) under ≤1×10−7 Torr vacuum. The near surface of the sample then undergoes a rapid melt and regrowth process using 2–10 pulses from a XeCl excimer laser. The laser has a 37‐ns pulse width at 308 nm and its energy density of 0.5–1.5 J/cm2 is precisely homogenized into a 4×4 mm square area. The alloy layers are 250–1600 Å thick, have a Ge fraction x=2.5–19%, and exhibit excellent crystallinity as evaluated by MeV ion channeling and lattice resolution cross‐sectional transmission electron microscopy. Unlike layer growth by molecular beam epitaxy, this approach is insensitive to minor levels of contamination because the original Ge/Si interface is melted through during the laser processing.