INFLUENCE OF OXYGEN BACKGROUND PRESSURE ON CRYSTALLINE QUALITY OF SRTIO3 FILMS GROWN ON MGO BY PULSED-LASER DEPOSITION

We have systematically investigated the effect of oxygen partial press ure (Pot) On the crystalline quality of SrTiO3 films grown on MgO (001 ) substrates using pulsed laser deposition and established optimized c onditions for the growth of high-quality epitaxial films. The crystall ine quality is found to improve significantly in the O-2 pressure rang e of 0.5-1 mTorr, compared to the films deposited at higher pressures of 10-100 mTorr. The x-ray diffraction rocking curves for the films gr own at PO2, of 1 mTorr and 100 mTorr yielded full width at half-maximu m (FWHM) of 0.7 degrees and 1.4 degrees, respectively. The in-plane x- ray phi scans showed epitaxial cube-on-cube alignment of the films. Ch anneling yields chi(min) Were found to be <5% for the 1 mTorr films an d similar to 14% for 100 mTorr films. Thermal annealing of the SrTiO3 films in oxygen further improves the quality, and the 1 mTorr films gi ve FWHM of 0.13 degrees and chi(min) of 1.7%. In-plane misorientations of the annealed SrTiO3 films calculated using results of transmission electron microscopy are +/-0.7 degrees for 1 mTorr and +/-1.7 degrees for the 10 mTorr film. The high temperature superconducting (high-T-c ) Y1Ba2Cu3O7-delta films grown on these SrTiO3/MgO substrates showed a chi(min) of 2.0% and transition temperature of similar to 92 K, indic ating that SrTiO3 buffer layers on MgO can be used for growth of high- quality Y1Ba2Cu3O7-delta thin film heterostructures for use in high-T- c devices and next generation microelectronics devices requiring films with high dielectric constants. (C) 1997 American Institute of Physic s.