Self-assembled CeO2 buffer layers on R-cut sapphire for high-current-density YBa2Cu3O7-delta films

摘要

Experimental evidence of a cooperative self-assembly process was obtained where high-temperature O-2 annealing (1000 degreesC) induced mass transport of CeO2 deposited on R-cut sapphire substrates to form a surface reconstruction on the substrate. When the CeO2 film exceeded a critical thickness (similar to10 nm), an atomically flat surface with a high density of nanodots was preferred by the reconstruction (revealed by scanning atomic force microscopy) and the CeO2 layers had high lattice and surface perfection (revealed by x-ray diffraction). YBa2Cu3O7-delta films grown on such CeO2-buffered sapphire substrates had a high transition temperature (T-c (p=o) > 90 K) and a high critical current density (J(c) > 3.0 x 10(6) A cm(-2) at 77.3 K and a zero applied magnetic field). [References: 18]