Independence of surface morphology and reconstruction during the thermal preparation of perovskite oxide surfaces

TL;DR

This study shows that surface morphology and reconstruction of perovskite oxide surfaces can be independently controlled during thermal preparation, enabling in situ epitaxy without ex-situ treatments across different materials.

Contribution

It demonstrates that large terrace formation occurs independently of surface reconstruction, and this process is universal for various perovskite oxides during thermal treatment.

Findings

Large terraces form at 900-1100°C independent of reconstruction

Surface reconstruction requires temperatures above 1200°C

Process applicable to SrTiO₃, LaAlO₃, and NdGaO₃ substrates

Abstract

Using a CO$_2$ laser to directly heat the crystals from the back side, SrTiO$_3$ substrates may be thermally prepared in situ for epitaxy without the need for ex-situ etching and annealing. We find that the formation of large terraces with straight steps at 900-1100 {\deg}C is independent from the formation of the ideal surface reconstruction for epitaxy, which requires temperatures in excess of 1200 {\deg}C to complete. The process may be universal, at least for perovskite oxide surfaces, as it also works, at different temperatures, for LaAlO$_3$ and NdGaO$_3$, two other widely used oxide substrate materials.