Post-annealed Thin Films Research Articles

Formation and characteristics of lead lanthanum zirconium titanate thin films formed by using the r.f. sputtering method

PLZT (lead lanthanum zirconium titanate) thin films were prepared by using the r.f. magnetron sputtering method and post-annealing for crystallization at 650 ‡C. The films which were annealed at 650 ‡C for 10 min consisted of a metastable phase and a stable phase. However, another film which was annealed at 650 ‡C for 20 min had only stable perfect perovskite phase. The stability of the post-annealed thin film and substrate interfaces was observed by using scanning electron microscopy. The longer the annealing time, the more unstable were the interfaces. By analysing the EDX data, the composition difference between the sputtering target and thin films, and the composition variation between as-deposited and post-annealed PLZT were studied. The films annealed at 650 ‡C for 20 min showed good ferroelectric and electrical properties with a remanent polarization (P r) of 11.5 ΜC cm−2, and a coercive field (E c) of 164 kV cm−1.

Defects in YBa2Cu3O7−δ Thin Films and Their Influences on Tc

AbstractCrystallographic defects introduced in the YBa2Cu3O7−δ thin films during depositions were studied using X-ray diffraction method, and their influences on superconducting properties were also investigated by examining Tc variation of the as-grown and post-annealed thin films. It was found that there exist several kinds of defects in the as-grown thin films, such as oxygen deficiency, cation disordering, and others like lattice dislocation, stacking faults, etc.. These defects could be relaxed by heat treatment at temperatures ranging from 400 to 900 °C, resulting in Tc enhancement more or less. Quantitative understandings of the relations among annealing temperature, structural relaxation, and Tc improvement has also been reached. The kinetics of the relaxation of the defects in the YBCO films was studied further using a high-temperature X-ray diffractometer. Interesting phenomena have been observed at around 400 °C due to abnormal desorption behavior of oxygen and at higher temperatures relating to cation ordering.

Direct measurements of the local electron transport properties in YBaCuO superconducting thin films

We have made measurements of the local potential distribution and topography of current carrying Y1Ba2Cu3O6.9 thin films using a scanning tunneling microscope. We have compared the electrostatic potential distribution in the normal state on post-annealed thin films and in-situ prepared films. On post-annealed films we find steps in the potential image indicative of insulating boundaries in the material which occur at boundaries between clusters of grains whereas the in-situ films show a nearly uniform potential drop. These results provide a clear indication of the nature of disorder in these thin films and what length scale ultimately determines the microscopic resistivity.