Intrinsic Josephson effect in biaxially-textured Bi-2212 thin films

Bi2Sr2CaCu2O8+x (Bi-2212) thin film with a thickness of micrometers was prepared by a sol-gel method using metal acetate as starting material. The crystal orientation and the superconducting properties of the thin film were studied. Besides, a pattern with a diameter of 300 µm and a thickness of 1.05 µm was prepared. The I-V curve indicates that the biaxially-textured Bi-2212 thin film has a zero-voltage overcurrent and shows a voltage jump under the zero-voltage current. These characteristics are similar to those of a single crystal and exhibit the unique Josephson effect of a intrinsic junction. In the superconducting state, the zero-voltage current increases linearly with the temperature decresing and the hysteresis area of the curve increases gradually. Further analysis indicates that its I-V characteristics are similar to those of a terahertz source device made from Bi-2212 single crystal. Based on these findings, it is predicted that it may generate THz waves with a frequency range of 0.144 THz-1.29 THz. The radiation frequency can be further regulated by controlling the thickness and bias voltage of the biaxially textured film as well as the envirmental temperature.