Fabrication of Ba1−xSrxTiO3 tunable capacitors with Tl2Ba2Ca1Cu2Ox electrodes

✍ Scribed by Ali Naziripour; Abdelkader Outzourhit; John U. Trefny; Z.-H. Zhang; Frank Barnes; Jay Cleckler; Allen M. Hermann

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 733 KB
• Volume: 233
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90767-6

✦ Synopsis

Tunable coplanar Bal _sr,TiO, (BSTO) thin-film capacitors with superconducting Tl-Ba-Ca-Cu-0 (22 12 ) electrodes have been successfully prepared using RF sputtering onto LaAIOs (100) substrates. The capacitors were fabricated in a five-step process consisting of: deposition of a Ba2CaCu20x precursor films on LaAIO, substrates; patterning of the precursor film into a planar capacitor with a gap of 5 to 40 km; formation of the superconducting phase by vapor-phase reaction with thallium; deposition of an amorphous BSTO overlayer onto the gap; and finally post-deposition annealing of the BSTO layer in flowing oxygen. The details of each fabrication step are presented, In addition, the structure, microstructure and composition of the films are analyzed. The temperature-and the voltage-dependence of the low frequency ( 10 kHz-100 kHz) capacitance and loss tangent are presented. A tunability of 101 at 77 K and 100 kHz was achieved. The capacitance-tunability results are compared with those obtained from YBCO-BSTO-YBCO capacitors.