Atomic layer engineering of perovskite oxides for chemically sharp heterointerfaces

TL;DR

This paper demonstrates that controlling oxygen pressure during pulsed laser deposition significantly improves the atomic sharpness of LaAlO3/SrTiO3 interfaces, enabling better strain management and coherent epitaxy in oxide heterostructures.

Contribution

It introduces a method to enhance interface sharpness in oxide heterostructures by optimizing oxygen pressure during growth, advancing interface engineering techniques.

Findings

High oxygen pressure improves interface abruptness.

Enhanced interface sharpness increases critical strain relaxation thickness.

Enables synthesis of more coherent and well-defined heterostructures.

Abstract

Advances in synthesis techniques and materials understanding have given rise to oxide heterostructures with intriguing physical phenomena that cannot be found in their constituents. In these structures, precise control of interface quality, including oxygen stoichiometry, is critical for unambiguous tailoring of the interfacial properties, with deposition of the first monolayer being the most important step in shaping a well-defined functional interface. Here, we studied interface formation and strain evolution during the initial growth of LaAlO3 on SrTiO3 by pulsed laser deposition, in search of a means for controlling the atomic-sharpness of the interfaces. Our experimental results show that growth of LaAlO3 at a high oxygen pressure dramatically enhances interface abruptness. As a consequence, the critical thickness for strain relaxation was increased, facilitating coherent epitaxy of perovskite oxides. This provides a clear understanding of the role of oxygen pressure during the interface formation, and enables the synthesis of oxide heterostructures with chemically-sharper interfaces.