CPM Seminar

Time-Resolved X-ray Studies of Pulsed Laser Deposition

Joel Brock

Department of Applied and Engineering Physics
Cornell University

X-ray scattering and reflectivity have been effectively used to measure the static atomic structure of surfaces and interfaces for several decades. Modern synchrotron x-ray facilities now deliver sufficient flux to make time-resolved measurements on a wide variety of evolving surface and interface systems feasible. In particular, time-resolved x-ray structural studies of Pulsed Laser Deposition (PLD) of SrTiO₃ have recently been shown to provide detailed insight into the fundamental, atomic-scale growth mechanisms. In addition to determining the growth mode, the surface/interface roughness, and the film thickness, some of the dynamics of the energetic collisions, the details of the subsequent nucleation and coarsening of islands, and the surface relaxation kinetics are now experimentally accessible with x-ray techniques. For example, our time-resolved GISAXS data demonstrate that in the layer-by-layer growth mode, nucleation of islands occurs only during the 1st pulse of a given layer. Subsequent pulses provide the additional material required for the coverage to increase, but do not nucleate additional islands. In this talk, I will discuss both our results and our evolving understanding of the fundamental growth physics differentiating PLD from other thin-film growth techniques.