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 pressure (Pot) On the crystalline quality of SrTiO3 films grown on MgO (001) substrates using pulsed laser deposition and established optimized conditions for the growth of high-quality epitaxial films. The crystalline quality is found to improve significantly in the O-2 pressure range 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 grown at PO2, of 1 mTorr and 100 mTorr yielded full width at half-maximum (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. Channeling yields chi(min) Were found to be <5% for the 1 mTorr films and similar to 14% for 100 mTorr films. Thermal annealing of the SrTiO3 films in oxygen further improves the quality, and the 1 mTorr films give 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, indicating 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 Physics.