AVS 59th Annual International Symposium and Exhibition
    Vacuum Technology Wednesday Sessions
       Session VT+AS+SS-WeM

Paper VT+AS+SS-WeM9
Characterization of Anisotropic Surface Morphology in Epitaxial Superconducting Thin Films by Wavelet Analysis

Wednesday, October 31, 2012, 10:40 am, Room 14

Session: Surface Analysis and Vacuum Manufacturing for Accelerators
Presenter: D.B. Beringer, The College of William and Mary
Authors: D.B. Beringer, The College of William and Mary
J.B. Hackett, The College of William and Mary
W.M. Roach, The College of William and Mary
R.A. Lukaszew, The College of William and Mary
Correspondent: Click to Email
Surface morphology and interface roughness are critical factors impacting the ultimate performance of many thin film materials and nano-scale devises. Next generation superconducting radio frequency (SRF) materials for particle accelerator cavities depend upon the ability to tailor and finely control the microstructure and morphology of superconducting / insulating /superconducting (SIS) multilayer thin film structures. The evolving surface of grown epitaxial thin films, influenced by nucleation and growth kinetics, may exhibit dendritic or fractal patterning where the resulting anisotropic features dominate a coarsening morphology. As such, a quantitative understanding of superconducting thin film morphology and the thin film deposition parameters leading to optimal SRF surfaces is desirable. Quantitative characterization of surface morphology is typically achieved with Fourier transform (FT) analysis and fractal characterization; however, this approach suffers intrinsic limitations as the FT is localized in the frequency domain and therefore cannot differentiate between specific features with isolated spatial coordinates. Wavelet analysis transcends these limitations by effectively isolating and quantifying surface features belonging to a designated length scale, thus enabling independent analysis of local surface features with varied spatial resolutions. Here we present our work with surface characterization by wavelet analysis of epitaxial superconducting Nb thin films.