GROWTH MODE OF EPITAXIAL SI0.5GE0.5 LAYER GROWN ON SI(100) BY ION-BEAMASSISTED DEPOSITION

The nucleation and growth of the Si0.5Ge0.5 alloy layer on Si (100) su bstrate during ion-beam-assisted deposition (IBAD) have been investiga ted by atomic force microscopy, reflection high-energy electron diffra ction, transmission electron microscopy, and double-crystal rocking di ffraction. We confirmed that Si0.5Ge0.5 nucleates on Si (100) via the Stranski-Krastanov (SK) mechanism by IBAD, and Ar-ion bombardment supp ressed SK growth mode as well as improved crystalline perfection. The epitaxial temperature was observed at 200 degrees C, and it was much l ower than the growth temperature (550-600 degrees C) in molecular-beam epitaxy (MBE). The chi(min) value (the ratio of channeling to random backscattering yields) was 10.5% lower than the obtained MBE value. Th e effect of ion bombardment on nucleation was explained as the result of ion-bombardment-induced dissociation of three-dimensional islands a nd enhanced surface diffusion, and appeared only at low deposition tem peratures where the dissociation of three-dimensional islands is more favorable than the formation of those islands. (C) 1995 American Insti tute of Physics.