Enhanced Depth Profiling of Perovskite Oxide: Low Defect Levels Induced in SrTiO3 by Argon Cluster Sputtering

• Published in: Journal of physical chemistry. C 2016-09, Vol.120 (38), p.21358-21363
• Main Authors: Ridier, Karl, Aureau, Damien, Bérini, Bruno, Dumont, Yves, Keller, Niels, Vigneron, Jackie, Etcheberry, Arnaud, Fouchet, Arnaud
• Format: Article
• Language: English
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.6b04007

We have studied the influence of the argon cluster ion sputtering technique in the X-ray photoelectron spectroscopy (XPS) depth-profiling analysis of a strontium titanate SrTiO3 (STO) substrate, chosen as a prototype perovskite-type oxide material. Unlike “standard” sputtering technique using monatomic ions, a gentle digging through STO (without inducing a large amount of defects) has been evidenced. Several improvements are evidenced by using this low-energy abrasion process: (i) the absence of argon implantation, (ii) the creation of very few oxygen vacancies which lead in the classical way to the lowering of oxidation states of titanium and the appearance of in-gap electronic states, and (iii) the preservation of the cationic stoichiometry. In addition, electrical measurements confirm that no metal–insulator transition is evidenced using the cluster ion source, unlike the case of the monatomic ion etching. Furthermore, for the latter case, a relaxation effect of the Ar+ ion induced electronic properties has been evidenced by combining XPS and transport measurements. Due to its unique depth-profiling features, the cluster ion sputtering technique offers new insights in the chemical and physical analysis of sensitive oxide surfaces and buried interfaces as in oxide heterostructures and superlattices.