All in situ deposition and characterization of YBa2Cu3O7−x thin films by low-energy electron diffraction and low-energy ion scattering spectroscopy

Abstract
In an ultrahigh vacuum apparatus, c‐axis oriented YBa2Cu3O7−x (YBCO) thin films were deposited by an ozone‐assisted reactive coevaporation method and characterized by low‐energy electron diffraction (LEED) and low‐energy ion scattering spectroscopy (LEISS). A clean surface with crystal perfection within the top two monolayers was confirmed by LEED for the first time. LEISS analysis showed that this clean surface is terminated by Cu(1)‐O chains. These experiments also indicate that the oxygen pressure and the vacuum condition are one of the essential factors in keeping an outermost surface clean.