BILAYER REFLECTION-HIGH-ENERGY-ELECTRON-DIFFRACTION INTENSITY OSCILLATIONS OBSERVED DURING GROWTH ON DOUBLE-DOMAIN SI(001) SURFACES

Bilayer reflection-high-energy-electron diffraction (RHEED) intensity oscillations were observed during growth on a double-domain Si(001) substrate during silicon gas-source molecular beam epitaxy (Si-GSMBE) using disilane. A transition from monolayer- to bilayer-mode oscillation behavior was observed in the [110] azimuth during growth. Oscillations began with an asymmetric monolayer waveform which transformed into an apparent bilayer mode following several oscillation periods. Simultaneous measurement of RHEED intensity oscillations of the specular beam and (1 X 2) and (2 X 1) reconstruction related beams in the [010] azimuth showed that the bilayer oscillations resulted from alternating surface reconstructions. The origin of these bilayer oscillations is discussed on the basis of the anisotropic growth kinetics on Si(001) surfaces.