Investigation of surface reconstruction domain behaviour during Si-GSMBE

Bilayer reflection-high-energy-electron diffraction (RHEED) intensity oscillations were observed during growth on a double-domain Si(001) (2×1)+(1×2) substrate during silicon gas source molecular beam epitaxy (Si-GSMBE) using disilane. A transition from monolayer to bilayer-mode oscillation behaviour was observed in the [110] azimuth during growth. Simultaneous measurement of RHEED intensity oscillations of the specular beam and (1×2) and (2×1) reconstruction related beams in the [010] azimuth showed that the bilayer oscillations resulted from alternating surface reconstructions. The emergence of these bilayer oscillations is discussed on the basis of the anisotropic growth kinetics on Si(001) surfaces. RHEED measurements on vicinal substrate were made and reveal that a preferential growth of type-B steps results in type-B domain predominance at expense of type-A domains. Temperature studies show that at substrate temperatures above 600°C this anistropy disappears and RHEED intensity variations resume “normal” monolayer-mode growth behavior.