Reconstruction of SrRuO$_{3}$ Films During Pulsed Laser Deposition*

SrRuO$_{3}$ (SRO) is a perovskite oxide conductor, widely used as an electrode in thin film systems due to its chemical and lattice compatibility. SRO thin films were grown on SrTiO$_{3}$ substrates by pulsed laser deposition and monitored with high-pressure reflection high-energy electron diffraction. High quality growth and flat films were confirmed with ex situ atomic force and scanning transmission electron microscopies. Oxygen growth pressures below $\sim $10 mtorr produced films that exhibited surface oxygen vacancies seen with scanning tunneling microscopy (STM). Typically, high oxygen pressures are employed to minimize oxygen vacancies, however for growth or post-annealing above $\sim $100 mtorr, in situ characterization by STM and low energy electron diffraction (LEED) revealed a surface reconstruction consisting of parallel rows with periodicity doubled in one direction. Density function theory (DFT) has found that additional oxygen can increase stability of a structure in which SrO rows buckle outward with excess oxygen bonding below. Reconstruction will affect film structures, interface properties, and screening.