Structural strain ina-axis oriented thin films studied by electron backscatter diffraction

Abstract

The electron backscatter diffraction technique has been used to study the depth distribution of the structural strain in a-axis oriented films made by a self-template method. It has been found that the structural strain was mainly formed in the upper layer near the interface between the template and upper layer. In contrast, there is little strain in the template layer. The strain can be relaxed when the thickness of the upper layer exceeds a certain value. The results agree with the observation of a dramatic improvement in the transition temperature and metallic behaviour when the upper layer was thicker than about 200 nm. Such a depth distribution of strain has been discussed in correlation with the degradation of in a-axis films. The microstructures of these films have been investigated by transmission electron microscopy.

Preparation of highly crystallinea-axis-oriented YBa2Cu3O7-δsuperconducting films by a self-template technique

“…The data in table 1 show that tendency of T c is increasing with the upper layer thickness. In [13], a dramatic improvement in the transition temperature and metallic behaviour was also observed when the upper layer was thicker than about 200 nm. Furthermore, the relatively short a-axis lattice parameter in the upper layer suggests that the strain is of tension in nature in the upper films.…”

“…Such an intermediate layer appears to consist of c-axis-oriented structures. Gao and Chen [13] suggested that the intermediate layer could be due to the growth dynamics rather than interaction.…”

“…The difference in the lattice parameter indicates the presence of the interfacial strain at the interface of the template and upper layers. Gao and Cheng [13] reported the observation of structural strain in a-axis-oriented thin films using an electron backscatter diffraction technique. In particular, they investigated the depth distribution of the strain and found that the structural strain was mainly formed in the upper layer near the interface between the template layer and upper layer.…”

“…Such an intermediate layer appears to consist of c-axis-oriented structures. Gao and Chen[13] suggested that the intermediate layer could be due to the growth dynamics rather than interaction.In this study we also found that the thickness of the template and the upper layer play an important role in determining the properties of the a-axis films. We made a series of samples with various template thicknesses under the optimal conditions (i.e.…”