Growth and electronic properties of nanolines on TiO2-terminated SrTiO3(001) surfaces

TL;DR

This study investigates the formation and electronic properties of nanolines on TiO2-terminated SrTiO3(001) surfaces, revealing their influence on band structure and defect states through in situ microscopy and spectroscopy.

Contribution

It demonstrates controlled formation of nanolines via Ti/Sr ratio adjustment and links surface nanostructures to electronic band modifications and defect states.

Findings

Nanolines cause increased band bending.

In-gap states are associated with oxygen vacancies.

Surface structure influences electronic properties.

Abstract

Surfaces of homoepitaxially grown TiO2-terminated SrTiO3(001) were studied in situ with scanning tunneling microscopy and spectroscopy. By controlling the Ti/Sr ratio, two-dimensional domains of highly ordered linear nanostructures, so-called "nanolines", are found to form on the surface. To further study how the surface structure affects the band structure, spectroscopic studies of these surfaces were performed. Our results reveal significantly more band bending for surfaces with the nanolines, indicative of an acceptor state associated with these features. Additionally, an in-gap state is observed on nanoline surfaces grown under high oxygen deficient conditions. This state appears to be the same as that observed previously, arising from the (++/+) transition level of surface oxygen vacancies.