Structural properties of ultrathin SrO film deposited on SrTiO₃

Abstract

The role of epitaxial strain and chemical termination in selected interfaces of perovskite oxide heterostructures is under intensive investigation because of emerging novel electronic properties. SrTiO 3 (STO) is one of the most used substrates for these compounds, and along its < 001 > direction allows for two nonpolar chemical terminations: TiO 2 and SrO. In this paper, we investigate the surface morphology and crystal structure of SrO epitaxial ultrathin films: from 1 to about 25 layers grown onto TiO 2-terminated STO substrates. X-ray diffraction and transmission electron microscopy analysis reveal that SrO grows along its ½111 direction with a 4% out-of-plane elongation. This large strain may underlay the mechanism of the formation of self-organized pattern of stripes that we observed in the initial growth. We found that the distance between the TiO 2 plane and the first deposited SrO layer is 0:27ð3Þ nm, a value which is about 40% bigger than in the STO bulk. We demonstrate that a single SrO-deposited layer has a different morphology compared to an ideal atomically flat chemical termination.

Surface Decorations on Mixed Ionic and Electronic Conductors: Effects on Surface Potential, Defects, and the Oxygen Exchange Kinetics

“… a Lattice parameters from literature − have been used to calculate the necessary amount of material to deposit 1.5 ML. …”

Oxygen surface exchange kinetics of La1−xSrxCoO3–δ thin-films decorated with binary oxides: links between acidity, strontium doping, and reaction kinetics

“…With strontium decorations, the optimum in oxygen exchange kinetics is reached at approximately 0.273 nm deposited 35 which in monolayers corresponds to approximately one monolayer of SrO. From the pristine state to one monolayer of SrO, the suggested explanation for the increase in k q is that further increasing Sr enrichment at the surface still decreases the Smith acidity, yielding an even more basic surface.…”

Advanced Epitaxial Lift‐Off and Transfer Procedure for the Fabrication of High‐Quality Functional Oxide Membranes

“…Substrate Preparation: (001)-oriented STO substrates were treated following the standard procedure in ref. [63] to obtain a TiO 2 -termination. After the chemical etching, they were first cleaned for 5 min in ultrasonic bath with successive solvents (acetone, ethanol, isopropanol, milliQwater, and isopropanol) and dried with an N 2 gun.…”