Atomic-Scale Monitoring of Step-Flow Growth During Perovskite Pulsed Laser Deposition

Aaron Fleet¹, Darren Dale², H.H. Wang¹, J.D. Brock¹, Y. Suzuki²

¹School of Applied & Engineering Physics

²Department of Materials Science & Engineering

Thin films of perovskite ceramics display a range of interesting magnetic properties, including superconductivity and colossal magneto-resistance. Despite polyatomic crystal unit cells, these materials exhibit “classical” growth modes during pulsed laser deposition. We grew thin films of EuTiO₃ on SrTiO₃ to study in a model system how complex crystals assemble “block-like” from constituent molecules.

The nearly perfect lattice match between EuTiO₃ and SrTiO₃ allows two-dimensional growth of strain-free films during pulsed laser deposition. We have observed ~50 “anti-Bragg” x-ray intensity oscillations during film growth, indicating that this system enters a steady state regime where two-dimensional growth can persist indefinitely, under optimal conditions. As a film grows, the specular crystal truncation rod exhibits an increasing number of interference (Kiessig) fringes, due to electronic density contrast between substrate and film. In this talk, I will discuss how the modulation of anti-Bragg intensity by interference fringes may enable precise monitoring of film thickness in the step-flow regime, enabling growth of atomically perfect structures. I will also present time-resolved simulations that allow extraction of features of film morphology from experimental data.

This work was supported by the Cornell Center for Materials Research, under National Science Foundation Grant No. DMR-9632275, and made use of facilities at the Cornell High Energy Synchrotron Source, NSF Grant No. DMR-9311772.

Full Talk (pdf, 2 MB)