Comparison between ultraviolet-photoelectron spectroscopy and reflection high-energy electron diffraction intensity oscillations during Si epitaxial growth on Si(100)

In ultraviolet-photoelectron spectroscopy on a Si(100) surface during solid-source or gas-source molecular-beam epitaxy (MBE), intensity oscillations of photoelectrons from the valence-band surface states are observed. Recent studies by authors [Enta et al., Surf. Sci. 313, L797 (1994)] have revealed that the photoelectron intensity oscillations (PIOs) most probably originate from an alternation between the 2×1 and the 1×2 surface reconstructions during growth. This model consequently suggests that the period of the oscillations corresponds to the growth time of 2 ML. To confirm this relation, reflection high-energy electron diffraction (RHEED) intensity oscillation was measured during gas-source MBE, using Si₂H₆ under identical growth conditions with those used for PIO observations. The oscillation period at the half-order diffraction spots of RHEED agreed well with that of PIO at various Si₂H₆ pressures, providing a direct support for the above interpretation for the origin of PIO.