Laser processing of YBCO thin films on sapphire for microwaveapplications

摘要

Laser ablation has been used to fabricate YBa2Cu3 O7-x(YBCO) thin film on sapphire substrates for microwave applications. The Interfaces between the YBCO laser ablated thin films and the r-plane Al2O3 substrates have been investigated by a transmission electron microscopy (TEM) and an Auger electron spectroscopy (AES) depth profile. The PrBa2Cu 3O7-x (PBCO) buffer layer has been used to prevent the interdiffusion. The interfaces of YBCO/Al2O3 and YBCO/PBCO/Al2O3 have been compared. The intermediate diffusion layer in the YBCO film deposited on bare sapphire was visible between the film and the substrate but no diffusion layer between the YBCO/PBCO thin film and the substrate was observed directly by the cross-section image of TEM. The thickness of the diffusion layer on bare sapphire is about 300 ?. This result of TEM is consistent with that of AES depth profile. We have fabricated a perturbed superconducting ring resonator on PBCO buffered sapphire for the microwave application. A fundamental resonance peak split was observed in the frequency range of 7.0-8.4 GHz