As-deposited superconducting Y-Ba-Cu-O thin films on Si, Al2O3, and SrTiO3 substrates

Abstract

We have developed an electron beam evaporator designed to deal with the special requirements of thin films of oxide superconductors. The growing surface is sprayed with plasma-excited oxygen while the sources and rate monitors operate in a low background pressure. This allows us to reproducibly grow films of Y-Ba-Cu-O on Si, Al2O3, and SrTiO3 substrates at a substrate temperature of 540 °C which are superconducting without the need for annealing. The resistive transitions of most films show an onset of 90 K and zero resistance by 68 K. X-ray diffraction indicates a preferred orientation for growth on most Si and SrTiO3 substrates. A preliminary measurement yields critical currents of at least 104 A/cm2 at 4.2 K for a film on silicon.

Buffer layers for superconducting YBaCuO thin films on silicon and SiO2

“…In contrast with reports in the literature [5,6,9, 10] we were not able to deposit crystalline 123 films with a thickness less than 1 /~m onto (100) Si. Although Venkatesan et al [9] reported only a slight intermixing of silicon and barium at the Si/123 interface, we have observed interfacial reactions at temperatures lower than those required to deposit crystalline 123.…”

“…By using oxygen plasmas even lower preparation temperatures can be achieved [6][7][8]. Although direct deposition of thin film 123 (less than 1 /~m) onto silicon substrates has been reported by several authors [5,6,9,10], the quality of the films is relatively poor. To obtain epitaxial films with high critical temperatures and currents, optimum deposition temperatures are found to be around 750°C and (100) SrTiO 3 substrates should be used Ill,12].…”

“…In situ preparation of superconducting 123 is possible by deposition in an oxygen background pressure at substrate temperatures of 650 °C and higher [4,5]. By using oxygen plasmas even lower preparation temperatures can be achieved [6][7][8]. Although direct deposition of thin film 123 (less than 1 /~m) onto silicon substrates has been reported by several authors [5,6,9,10], the quality of the films is relatively poor.…”

Electronic transport properties of (001)/(110) oriented La2/3MnO3−δ thin films

“…3 Lanthanum-deficient La 2/3 MnO 3Ϫ␦ thin films were grown on Al 2 O 3 (11 02) and SrTiO 3 ͑100͒ using electronbeam coevaporation. 11 Our previous studies on La 1Ϫx Ca x MnO 3 and La 1Ϫx K x MnO 3 using the same technique were reported elsewhere. 12,13 In brief, we used two electron beam sources to evaporate La and Mn.…”

Origin of surface layer on common substrates for functional material films probed by ellipsometry

“…Specifically, sometimes just damaged layer on sapphire substrate prevented the growing film to get proper orientation. The X-ray data of depositions on sapphire substrates showed that the growth had no preferable orientation [2]. The X-ray analysis showed that as-deposited films were amorphous [3].…”