The characterization of SrTiO3 thin films, deposited onto SrTiO3 substrates by pulsed-laser deposition, was performed by exploiting Doppler broadening of the annihilation radiation as detected using variable energy positron beam measurements. The laser repetition rate and the post-growth annealing conditions were varied. The variable energy positron beam measurements clearly detected the deposited SrTiO3 layer. The increase in the Doppler broadened line shape parameter S, as compared to the substrate, was about 3.5%. Also revealed was the presence of a high concentration of open-volume defects. The magnitude of the change in S, and a lack of dependence upon O partial pressure during annealing provided evidence that Sr vacancies and VSr-O vacancy defects were responsible for the positron trapping. Some of the films were also carefully studied using transmission electron microscopy. Fitting of the variable-energy positron beam profiles, using thickness data obtained via transmission electron microscopy, provided evidence that the homogeneous growth region, observed by transmission electron microscopy, had a lower vacancy content when compared to the surface columnar region.

Variable Energy Positron Beam Analysis of Vacancy Defects in Laser Ablated SrTiO3 Thin Films on SrTiO3. S.McGuire, D.J.Keeble, R.E.Mason, P.G.Coleman, Y.Koutsonas, T.J.Jackson: Journal of Applied Physics, 2006, 100[4], 044109 (6pp)