Growth of YBa2Cu3O7 on silicon and LaAlO3 with MgO buffer layers

Thin films of YBa2Cu3O7 (YBCO) have been grown on MgO buffer layers on LaAl O3 and silicon substrates by laser ablation at substrate temperatures of 75 0 degrees C in a 250 mTorr oxygen atmosphere. The films grown on MgO/LaAlO3 are c-axis oriented and epitaxial, as shown by X-ray measurements. The fil ms grown on MgO/Si have mixed a-, b-, and c-axis orientation. For YBCO/MgO/ Si the presence of the MgO buffer layer cannot be detected by X-ray diffrac tion, suggesting a possible reaction between the Si and MgO at elevated tem peratures. Pole figures show the YBCO growth on Si to be epitaxial with a s ignificant in plane random component. Resistivity measurements indicate tha t the transition temperature of the YBCO/MgO/LaAlO3 is 87 K, while the tran sition temperature for YBCO/MgO/Si is lower, 85 K, probably due to the poor epitaxy of the film. (C) 1999 Published by Elsevier Science B.V. All right s reserved.