Ex-situ atomic force microscopy on the growth mode of SrRuO3 epitaxial thin film

TL;DR

This study uses ex-situ atomic force microscopy to investigate the initial growth mechanisms of SrRuO3 thin films on SrTiO3, revealing layer-by-layer growth and possible half-unit cell formation crucial for high-quality epitaxial films.

Contribution

It provides new insights into the heteroepitaxial growth process of SrRuO3, highlighting the formation of half-unit cells and layer-by-layer growth during initial deposition.

Findings

Layer-by-layer growth mode during first two unit cells.

Possible formation of half-unit cell before complete unit cell.

Surface roughness variations indicating growth dynamics.

Abstract

The functional properties of devices based on perovskite oxides depend strongly on the growth modes that dramatically affect surface morphology and microstructure of the hetero-structured thin films. To achieve atomically flat surface morphology, which is usually a necessity for the high quality devices, understanding of the growth mechanism of heteroepitaxial thin film is indispensable. In this study, we explore heteroepitaxial growth kinetics of the SrRuO3 using intermittent growth scheme of pulsed laser epitaxy and ex-situ atomic force microscopy. Two significant variations in surface roughness during deposition of the first unit cell layer were observed from atomic force microscopy indicating the possible formation of the half unit cell of the SrRuO3 before the complete formation of the first unit cell. In addition, layer-by-layer growth mode dominated during the first two unit cell layer deposition of the SrRuO3 thin film. Our observation provides underlying growth mechanism of the heteroepitaxial SrRuO3 thin film on the SrTiO3 substrate during the initial growth of the thin film.