Non-c-axis-Oriented EuBa₂Cu₃O_7-δ Thin Films Grown on Al₂O₃(11̄02) Substrates with CeO₂ Buffer Layers

Abstract

EuBa 2 Cu 3 O 7−δ (EBCO) thin films with different growth orientations were prepared on Al 2 O 3 (1102) substrates with CeO 2 buffer layers by dc magnetron sputtering. The EBCO thin films were deposited immediately after off-axis rf magnetron sputtering of CeO 2 (001) films. The effects of substrate temperature and oxygen concent on epitaxial orientation of EBCO thin films were examined. With the increase in oxygen concentration, the surface roughness of an EBCO thin film increased. An appropriate oxygen concentration existed. It was clarified that the orientation of an EBCO thin film depended on CeO 2 film thickness. The (100)-and (110)-oriented EBCO thin films were obtained on CeO 2 buffer layers 30-90 Å thick and more than 700 Å thick, respectively. The (100)-and (110)-oriented EBCO films had in-plane epitaxial orientation relationships of Al 2 O 3 [1120] CeO 2 [100] EBCO[013] and Al 2 O 3 [1120] CeO 2 [100] EBCO[110], respectively. The (100)-oriented EBCO films deposited on 50-Å-thick CeO 2 (001) buffer layers had T ce 's of 72.0 K, and (110)-oriented EBCO films deposited on 750-Å-thick CeO 2 (001) buffer layers had T ce 's of 70.0 K. The T ce decreased with increasing CeO 2 buffer layer thickness above 800 Å. The a-axis-oriented EBCO thin films exhibited T ce 's of about 85.4 K on the 50-Å-thick CeO 2 buffer layers prepared by a self-template method.KEYWORDS: EuBa 2 Cu 3 O 7−δ thin film, CeO 2 buffer layer, sapphire substrate, magnetron sputtering, self-template method 5857

Epitaxial Non c-Axis Twin-Free Bi2Sr2CaCu2O8+δ Thin Films for Future THz Devices

“…Thin films are also thought to be more useful than bulk crystals for integration purposes and, in fact, a non c -axis film can be viewed as an organized structure of many nano or micro scale crystals with the same orientation and quality. It is also worthy to mention that integration of thin films with different orientations into heterostructures [12,13,14,15,16] promotes formation of novel synergetic effects at interfaces that are useful for the development of new devices.…”