We have investigated the atomically-resolved substrate and homoepitaxial thin film surfaces of SrTiO3 (001) using low-temperature scanning tunneling microscopy/scanning tunneling spectroscopy (STS) combined with pulsed laser deposition. It was found that a typical annealing treatment for preparation of SrTiO3 substrates, unexpectedly, resulted in a disordered surface on an atomic scale. In contrast, homoepitaxial SrTiO 3 thin films grown on this disordered substrate exhibited a (2×2) surface reconstruction. The STS measurements revealed a number of surface defects in a 10 unit cell thick SrTiO3 film but much fewer in a 50 unit cell thick film, indicating nonuniform stoichiometry along the growth direction. These results suggest the possibility of using homoepitaxial SrTiO3 film surfaces as idealized substrates, opening a way to extract novel functionalities in complex oxides heterostructures.
ASJC Scopus subject areas
- Physics and Astronomy(all)