Preparation of highly crystallinea-axis-oriented YBa₂Cu₃O_7-δsuperconducting films by a self-template technique

Abstract

We have prepared high-quality a-axis-oriented superconducting YBa 2 Cu 3 O 7−δ (YBCO) films using a self-template method on (100) SrTiO 3 (STO) substrates by dc sputtering. X-ray diffraction and transmission electron microscopy analysis showed that the films were grown epitaxially on the STO substrates with the a-axis perpendicular to the surface. The full-width at half-maximum value of 0.081 was measured through the rocking curve of the (200) diffraction peak. The effect of the deposition temperature and the thickness of the template layer and the upper layer on the quality of the films was investigated. We found evidence suggesting that structural strain was present at the interface between the template layer and the upper layer. For the film deposited under optimal conditions, the zero-resistance T c was 85 K and the transition width was less than 2 K. The anisotropy of normal state resistance and critical current density was also studied.

Growth of twin-free b-oriented YBa2Cu3O7 − x films

“…These films are traditionally grown с-oriented due to the relative simplicity of their growth technique [4]. However, recently much attention has been paid to а-oriented YBa 2 Cu 3 O 7 − x films [5][6][7][8][9][10][11], which have a higher application potential for quantum devices (including sandwich-type Josephson junctions) than c-oriented films, because the coherence length in the directions perpendicular to the с axis (1.5−2.0 nm) is much larger than along the c axis (0.2−0.3 nm) [13,14]. The reduction and disappearance of c-oriented domains, depending, e.g., on the growth conditions, were thoroughly investigated [5,14].…”

Supersaturation-Controlled Growth Orientation and Grain Boundary Transition in REBa2Cu3O7−δ (RE = Sm, Sm1−xYx) Liquid-Phase Epitaxial Films

“…On one hand, microelectronic devices based on the superconductor/insulator/superconductor (SIS) Josephson junctions require a / b -axis perpendicular to the substrate. There are numerous papers reporting growth of a -axis oriented films by different methods, such as pulsed laser deposition (PLD), − sputtering, , or liquid-phase epitaxy (LPE). − On the other hand, coated conductors prefer c -oriented grains, and a great effort is made to avoid a -oriented phase during the preparation …”