  The functional properties of devices based on perovskite oxides depend
strongly on the growth modes that dramatically affect surface morphology and
microstructure of the hetero-structured thin films. To achieve atomically flat
surface morphology, which is usually a necessity for the high quality devices,
understanding of the growth mechanism of heteroepitaxial thin film is
indispensable. In this study, we explore heteroepitaxial growth kinetics of the
SrRuO3 using intermittent growth scheme of pulsed laser epitaxy and ex-situ
atomic force microscopy. Two significant variations in surface roughness during
deposition of the first unit cell layer were observed from atomic force
microscopy indicating the possible formation of the half unit cell of the
SrRuO3 before the complete formation of the first unit cell. In addition,
layer-by-layer growth mode dominated during the first two unit cell layer
deposition of the SrRuO3 thin film. Our observation provides underlying growth
mechanism of the heteroepitaxial SrRuO3 thin film on the SrTiO3 substrate
during the initial growth of the thin film.
