YBa2Cu3O7−δ films on Si with Y-stabilized ZrO2 and Y2O3 buffer layers: High-resolution electron microscopy of the interfaces

Abstract

The interfaces of YBa2Cu3O7−δ (YBCO) thin films grown on Si substrates with Y-stabilized ZrO2 (YSZ) and Y2O3 buffer layers have been studied by high-resolution electron microscopy. At the Si-YSZ interfaces a 4-nm-thick amorphous silica layer is found, bridged by 10-nm-wide crystalline YSZ regions. Close to these regions the Si substrate contains planar {111} faults. At the YSZ-Y2O3 interfaces perfect misfit dislocations are present, with Burgers vector 1/2〈110〉. They occur either as separated single dislocations or as separated groups of closely spaced dislocations. The atomic coordination at the planar and atomically sharp Y2O3-YBCO interface could be revealed. The first atomic layer of the YBCO is found to be a Ba layer.

High-resolution electron microscopy of epitaxial YBCO/Y2O3/YSZ on Si(001)

“…11 In this paper we present more detailed results obtained by high-resolution electron microscopy (HREM). The high Jc values of the films are related to the successful epitaxial growth, and thus to the relatively perfect interfaces that are present.…”

Yttria stabilized zirconia buffered silicon: substrates for YBCO microwave applications

“…They observed that with a 1.7 nm thick native oxide, highly (001) oriented YSZ films grew with grains having significant in-plane misalignment. It was observed that the SiO 2 layer experienced some re-growth and was 4 nm thick after deposition, as measured by high-resolution transmission microscopy (HRTEM) [68]. Mathee et al concur with this result except that they found in growing the YSZ film, if the oxygen pressure is kept very low (<7.5 x 10-' Torr) during the first 10 A of growth, the native oxide is significantly reduced by the following reaction [54]:…”

“…This has the effect of lower conductivity in the sintered target as compared to the hot-pressed target. YSZ is known to have a large oxygen diffusion coefficient of 2 x 10-9 cm 2 /s [68,69]. This causes the oxygen deficient target to respond differently during sputtering.…”

ArF and KrF excimer laser deposition of yttria-stabilized zirconia on Si(100)

“…Fork et al 5 obtained the best films reported on hydrogen terminated silicon, but other groups have reported epitaxy on uncleaned substrates. Bardal et al 3 deposited films by electron beam evaporation starting at the base pressure and introducing oxygen after the early stages of growth. They explained the epitaxial growth considering that the partially reduced YSZ deoxidized the surface.…”