Fabrication of carrier controlled Y1−xCaxBa2Cu3O7−δ films on SrTiO3(100) substrate by pulsed laser deposition

Abstract Ca-doped ( x =0, 0.1, 0.2, and 0.3) Y 1− x Ca x Ba 2 Cu 3 O 7− δ films were fabricated on SrTiO 3 (1 0 0) substrate by pulsed laser deposition technique. The optimal deposition temperature and oxygen partial pressure were found to be 780°C and 400 mTorr, respectively. The films prepared in this manner exhibit excellent crystallinity and smooth surface morphology. The superconducting transition temperature ( T c ) is found to decrease with increasing Ca content. The c -axis length was found to be insensitive with dopant concentration. We fabricated a series of samples by annealing at reduced oxygen pressures in order to study the dependence of carrier concentration on the oxygen deficiency, δ . The Ca content of those samples were 30% which is the solid solubility limit of Ca-doped YBa 2 Cu 3 O 7− δ . The increase of T c with increasing δ was attributed to the effect of overdoping. Although the films were overdoped, majority of the carriers supplied by Ca were found to be compensated by the creation of oxygen vacancies.