Graphoepitaxial Y:ZrO2 films on vicinal (110) NdGaO3 substrates by pulsed laser deposition

Thin films of Y:ZrO2 (YSZ) have been grown on vicinal NdGaO3 substrates (tilted by 0 degrees-3 degrees around [001] NdGaO3 from (110) plane toward (010) plane) by pulsed laser deposition. The surface of the films is smooth, the signs of step-flow growth mode can be detected for small tilt angles < 0.2 degrees. The orientation of the films followed graphoepitaxial matching with the substrates for all studied tilt angles down to 0.06 degrees. In case of arbitrary in-plane orientation of the tilt axis, the graphoepitaxial growth mode was observed in both substrate in-plane directions. The thin YSZ films showed narrow rocking curves and contracted c lattice constant normal to the (110) plane. An increase of film thickness results in relaxation of c to 5.142 angstrom, in a good agreement with the bulk value for the target composition of 9 mol% Y2O3:ZrO2. The width of the rocking curve increases with thickness to a relatively high level similar to 3 degrees. Both thickness dependences show exponential saturation with characteristic thicknesses 13-19 nm. The reason for such a behavior is probably the gradual relaxation of the substrate-induced strain with thickness by generation of dislocations.

Automated summary

Thin films of Y:ZrO2 (YSZ) were grown on vicinal NdGaO3 substrates by pulsed laser deposition with smooth surfaces and step-flow growth mode detected for small tilt angles. The films showed good graphoepitaxial matching with the substrates for all studied tilt angles and exhibited a contracted lattice constant normal to the (110) plane with increasing film thickness, reaching a characteristic thickness for exponential saturation of rocking curves. The relaxation of substrate-induced strain with thickness likely involves the generation of dislocations.