Epitaktisches Wachstum des Hochtemperatursupraleiters YBa$_{2}$Cu$_{3}$O$_{7}$, auf Siliziumeinkristalien mit Pufferschichten

In this work the growth of thin films of the high-temperature superconductor YBa$_{2}$Cu$_{3}$O$_{7}$ on Si(001) substrates has been investigated by Rutherford backscattering, channeling, X-ray diffraction, high resolution transmission electron microscopy, and electrical measurements. Epitaxial buffer layers of electrically insulating, pure andyttria-stabilized ZrO$_{2}$ ($\vert$Y$_{2}$O$_{3}$$\vert$$_{0.06}$$\vert$ZrO$_{2} \vert$$_{0.94}$ = YSZ) as well as of metallic CoSi$_{2}$ were employed to largely prevent the interdiffusion and chemical reaction between the superconductor film and the substrate in spite of the high deposition temperatures of the YBa$_{2}$Cu$_{3}$O$_{7-x}$ in the range of 600 to 800 $^{\circ}$. The electron beam evaporated ZrO$_{2}$ and YSZ films grew epitaxially on Si(001) with a high degree of crystalline perfection as indicated by channeling mimimum yield values of 7 and 6 % respectively. The YSZ exhibited a cubic structure, whereas in the case of the pure ZrO$_{2}$ the monoclinic baddeleyite structure was observed, resulting in films with an increased surface roughness. In both cases the in-plane axes of the films are essentially parallel to the corrlated YBa$_{}$aser abesponding directions of the substrate. With respect to the high degree of crystalline perfection of the films an unintentional removal of the native SiO$_{2}$ seems probable. It is possibly achieved by a chemical reaction of the SiO$_{2}$ with incoming Zr or ZrO originating from the partial decomposition of the pellet under the influence of the electron beam. [...