Ultrathin Deposition of Copper on Room Temperature SrTiO3(100)

An SrTiO3(110) surface was prepared and characterized under ultraclean conditions in ultrahigh vacuum. The methods used were Auger electron spectroscopy, electron energy loss spectroscopy, UV photoelectron spectroscopy and high resolution electron energy loss spectroscopy and low energy electron diffraction. Copper was gradually deposited at room temperature by electron beam evaporation upon a (1 x 1) SrTiO3(110) surface, until several monolayers were reached. Although charging effects disturb the Auger measurements, it is possible to determine that room temperature growth mode is of the Volmer-Weber type (islanding) and non-epitaxial. Five well-defined energy losses are attributed to interband transitions and plasmons in the range below 30 eV while the UV photoelectron spectra showed three strong peaks characteristic of Cu3d and O2p bands, with copper appearing as an impurity of the band gap. It is suggested that the formation of islands is associated with TiO2-terminated layers at the surface. The copper is weakly bound to the substrate and desorbs at 500C.