The Effect of Polyethyleneimine (PEI) on the Texture and Morphology of YBCO Films

Abstract

The effect of polyethyleneimine (PEI) in precursor solution on the morphology and superconducting properties of YBa2Cu3O7-x (YBCO) films grown on LaAlO3 (LAO) substrates by metal-organic deposition (MOD) method was investigated. The morphologies of the YBCO films were different based on the different amount of PEI addition from 0.25 g to 0.9 g in 10 mL precursor solution. Furthermore, research results indicate that the PEI helps to improve the critical current density (Jc), the uniformity of surface morphology and c-axis orientation of thin film. The highest critical current density (Jc) of 2.17 MA/cm2 at 77 K is obtained in YBCO films fabricated on LAO substrates when the amount of PEI is 0.5 g in 10 mL precursor solution. YBCO layers with about 400 nm in thickness can be processed without cracks and holes during the whole heat treatment, which takes only 7.5 h.