Abstract
Highly epitaxial, microcrack-free thin films of YBa 2Cu 3O 7 − δ (YBCO) have been grown by pulsed laser deposition on sapphire substrates with a double buffer of Y 2O 3/CeO 2. The Y 2O 3 layer, which has excellent compatibility with CeO 2 and YBCO, has been found to be beneficial in reducing the surface porosity of YBCO films as well as inhibiting a-axis-oriented epitaxial growth. The reduction in porosity is attributed to the presence of the Y 2O 3 layer which acts as a suitable barrier for the chemical reaction occurring at high deposition temperatures between YBCO and CeO 2. Due to the improvement in film quality and surface morphology, enhancement of the self-field critical current density ( J c, 77.3 K) by as high as 30% was obtained for a 650-nm thick YBCO film deposited on Y 2O 3/CeO 2 bi-layer buffer compared to simultaneously-deposited YBCO film on CeO 2 single-layer buffer only.
Published Version
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