Atomically flat, ultrathin-SiO2/Si(001)interface formation by UHV heating

Conventional wet cleaning and ultrahigh vacuum (UHV) heated cleaning prior to thermal oxidation were compared with respect to their effects on extremely thinSiO2/Si(001)interface roughness. Atomically flatSiO2/Si(001)interfaces were realized by preparing theSi(001)−2 × 1surface in UHV followed by thermal oxidation. This planarization is significant in the range of oxide thickness (Tox < ∼ 9nm). As for the ‘wet-cleaned’ surfaces, a wide variety of the interface roughness was observed atTox < ∼ 4nmwhich corresponds to the ‘initial oxide thickness (Tio)’ which appeared in the oxide growth kinetics. The electron scattering caused by the interface roughness might degrade the inversion electron mobility for the ‘wet-cleaned’ sample atTox < Tio.