Growth control of oxygen stoichiometry in homoepitaxial SrTiO3 films by pulsed laser epitaxy in high vacuum

TL;DR

This study demonstrates that by controlling plume kinetic energy during pulsed laser epitaxy, high-quality SrTiO3 films with proper oxygen stoichiometry can be grown in high vacuum, overcoming previous challenges.

Contribution

It introduces a method to control oxygen stoichiometry in SrTiO3 films grown in high vacuum by adjusting laser plume energetics, enabling defect-free crystalline films.

Findings

Oxygen vacancy generation is influenced by laser plume energetics.

Proper laser beam delivery controls oxygen defects.

Method applies to high vacuum growth of STO films.

Abstract

In many transition metal oxides (TMOs), oxygen stoichiometry is one of the most critical parameters that plays a key role in determining the structural, physical, optical, and electrochemical properties of the material. However, controlling the growth to obtain high quality single crystal films having the right oxygen stoichiometry, especially in a high vacuum environment, has been viewed as a challenge. In this work, we show that through proper control of the plume kinetic energy, stoichiometric crystalline films can be synthesized without generating oxygen defects, even in high vacuum. We use a model homoepitaxial system of SrTiO3 (STO) thin films on single crystal STO substrates. Physical property measurements indicate that oxygen vacancy generation in high vacuum is strongly influenced by the energetics of the laser plume, and it can be controlled by proper laser beam delivery. Therefore, our finding not only provides essential insight into oxygen stoichiometry control in high vacuum for understanding the fundamental properties of STO-based thin films and heterostructures, but expands the utility of pulsed laser epitaxy of other materials as well.