Monolayer oscillation observed by an oblique-incidence reflectance difference technique for the epitaxial growth of oxides

We report the optical oscillations with monolayer periodicity observed by a n oblique-incidence reflectance difference (OIRD) technique on the epitaxia l growth of Nb-doped SrTiO3 on SrTiO3 substrate. The periodicity was verifi ed by the simultaneously measured reflection high-energy electron diffracti on intensity oscillations. The OIRD oscillation damps during deposition, bu t can recover after the growth is interrupted for some time. We interpret t he optical oscillations as a result of the periodic changes of the surface morphologies due to the two-dimensional layer-by-layer growth of thin films .