Enhanced current carrying ability for GaBa_2Cu_3O_(7-x) films deposited with negative bias by RF magnetic sputtering method

摘要

GaBa_2Cu_3O_(7-x) films were prepared on LaAlO_3 substrate by RF magnetic sputtering with different temperature and negative bias from 800 to 860 °C and 0 v to - 90 v, respectively. We investigate the relationship between temperature and negative bias and the performance of the film to analyze the most suitable deposition conditions. The surface texture and structure of GaBa_2Cu_3O_(7-x) films were observed by X-ray diffraction (XRD), Raman measurement, field emission scanning electron microscope (FESEM). The superconducting properties were measured by physical property measurement system (PPMS). It was found that the structure, surface morphology, and superconducting property of GaBa_2Cu_3O_(7-x) film are seriously affected by the temperature and negative bias. The crystallinity and surface quality of the film first increases and then decreases with the increase in the deposition temperature, and reach the best at 840 °C. In order to further improve the performance of the film, a negative bias voltage of 0 to - 90v was applied on the basis of this temperature, and the best quality film was obtained under a negative bias of - 30 v. The surface of the film prepared under the conditions of 840 °C and - 30v is the most dense and uniform, and the critical current density reaches 0.16MA/cm~2, which is almost 3 times higher than that of the film prepared without negative bias.