Realization of Y 1Ba 2Cu 3O 7−δ/Y-ZrO 2 epitaxial configuration on silicon (100) by pulsed laser ablation without chemical removal of native surface oxide

Abstract

Epitaxial growth of Y-ZrO 2 buffer layer followed by that of the high- T c Y 1Ba 2Cu 3O 7−δ on Si (100) substrate has been realized by pulsed excimer laser ( λ=248 nm) ablation, without chemical removal of the native surface oxide on silicon. The influence of substrate surface preparation conditions and the substrate temperature on the crystallinity and quality of the Y-ZrO 2 buffer layers has been examined. it is observed that cubic Y-ZrO 2 films can be deposited epitaxially on Si (100) without chemical removal of the thin native oxide if the deposition is carried out at 800°C, initially at a reduced oxygen pressure (1 x 10 −6 Torr) followed by a deposition at higher pressure (5 x 10 −4 Torr). The crystalline qualities of the deposited films have been studied by X-ray diffraction, high resolution transmission electron microscopy (HREM) and Rutherford backscattering channeling techniques. The X-ray results reveal the high degree of c-axis orientation normal to the film surface. The χ min in the channeled RBS spectrum has been found to have values of 8% and 13% for Y-ZrO 2 and Y 1Ba 2Cu 3O 7−δ films, respectively. The HREM results on the Y-ZrO 2/ Si interface show that the epitaxial layer of Y-ZrO 2 is separated from the crystalline silicon substrate by a few nanometer bridging layer of amorphous (or microcrystalline) SiO x . Typically, the superconducting films of thickness 5000 Å deposited on silicon with a 1500 Å epitaxial Y-ZrO 2 buffer layer have T c as high as 88 K and J c of more than 10 5 A/cm 2 at 77 K.