[Jlabsa_gs] **Reminder** Pizza Seminar - Wednesday, January 21, 2015 - A Message From Hari Areti

Jodi Patient patient at jlab.org
Tue Jan 20 08:13:12 EST 2015


Jefferson Lab's Graduate Student and Post-Doc Association Wiki:
  https://gspda.jlab.org/wiki/index.php/Main_Page

         Please RSVP to:  patient at jlab.org by COB on January 20, 2015

                         Wednesday, January 21 , 2015

                                   ***F113***

                                  12:00-1:00 pm

                                   John Musson

                                  Jefferson Lab



"Deposition of Superconducting Nb Thin Films by Recrystallization and Abnormal Grain Growth"


Abstract:  Superconducting (SC) niobium (Nb) thin films provide an attractive solution to 
accelerator cavity manufacturability, but so far have been deficient in their radio-frequency 
(RF) performance. Physical vapor deposition (PVD) techniques, such as sputtering, have been 
largely favored, but have nearly always resulted in finite surface impedances, and lower 
residual resistance ratios, (RRR) than bulk Nb. Recently, energetic condensation, and the use
of cold substrates has supported an alternative method for film growth, whereby an amorphous 
film is grown beyond the thickness during which grain competition is completed. Laser-induced 
re-crystallization of the film surface results large-grain crystalline structure, resembling 
bulk Nb. In addition, abnormal grain growth in thin films is explored, whereby the interface 
energies and initial film thicknesses are manipulated to favor radial (2-D) grain growth. The 
resulting large-grain Nb (110) film provides a template for homo-epitaxial deposition, in order 
to create thicker bulk-like SC films.


More information about the Jlabsa_gs mailing list