Influence of oxygen pressure and aging on LaAlO3 films grown by pulsed laser deposition on SrTiO3 substrates

TL;DR

This study compares the crystal structures of LaAlO3 films grown on SrTiO3 substrates at different oxygen pressures, revealing that lower oxygen pressure results in sharper interfaces and that aging induces crystalline phase formation without changing layer thickness.

Contribution

It demonstrates how oxygen pressure influences interface sharpness and phase formation in LaAlO3/SrTiO3 heterostructures, providing insights into growth conditions and aging effects.

Findings

Lower oxygen pressure yields sharper interfaces.

Aging leads to crystalline phase formation.

Crystalline thickness remains unchanged over time.

Abstract

The crystal structures of LaAlO3 films grown by pulsed laser deposition on SrTiO3 substrates at oxygen pressure of 10-3 mbar or 10-5 mbar, where kinetics of ablated species hardly depend on oxygen background pressure, are compared. Our results show that the interface between LaAlO3 and SrTiO3 is sharper when the oxygen pressure is lower. Over time, the formation of various crystalline phases is observed while the crystalline thickness of the LaAlO3 layer remains unchanged. X-ray scattering as well as atomic force microscopy measurements indicate three-dimensional growth of such phases, which appear to be fed from an amorphous capping layer present in as-grown samples.