Time Resolved In-Situ Diffuse X-ray Scattering Measurements of the Surface Morphology of Homoepitaxial SrTiO3 Films During Pulsed Laser Deposition

Abstract

Homoepitaxial SrTiO3 thin films were grown on SrTiO3 (001) using Pulsed Laser Deposition (PLD). The deposition process was monitored in-situ, via both x-ray reflectivity and surface diffuse x-ray scattering measurements in the G3 experimental station at the Cornell High Energy Synchrotron Source (CHESS). Using a CCD detector in 1D, or streak-camera, mode with approximately 0.3-second time resolution, data were collected during growths performed at two substrate temperatures: 695°C and 1000°C. While the specular reflectivity oscillations for the two growths are very similar, the diffuse scattering clearly shows a distinct change in the peak position. Using Atomic Force Microscopy (AFM), we illustrate how the peak position for the diffuse lobes of scattered intensity is directly related to the distribution of single unit cell high islands on the growing surface. Thus, the peak shift of the diffuse scattering indicates an order of magnitude change in the island density.

A method of material design for systematic absence of X-ray diffraction

“…Materials with systematic absence of specific diffraction peaks are needed for solving some special problems in many XRD experiments or time-resolved X-ray scattering ͑TRXRS͒ experiments ͑Fleet et al., 2005;Tischler et al, 2006;Ferguson et al, 2008͒. One example is using XRD to solve the unknown structure of an ultrathin film whose metastable phase cannot exist independently in a bulk state. In this situation, a substrate with both equally symmetric lattice and systematic absence of the corresponding diffraction peaks is highly desirable.…”