Vacancy clusters at domain boundaries and band bending at the SrTiO$_3$(110) surface

TL;DR

This study investigates how vacancy clusters at domain boundaries on SrTiO$_3$(110) surfaces influence band bending, using microscopy, spectroscopy, and DFT calculations to understand their formation, stability, and control via oxygen pressure.

Contribution

It provides detailed structural models of vacancy clusters at domain boundaries and demonstrates how their manipulation can tune surface band bending.

Findings

Vacancy clusters are formed by Ti$_x$O$_y$ with specific stoichiometry.

Their stability depends on oxygen chemical potential.

Surface band bending can be controlled by vacancy cluster manipulation.

Abstract

Antiphase domain boundaries (APDBs) in the ($n \times 1$)($n=4,5$) reconstructions of the SrTiO$_3$(110) surface were studied with scanning tunneling microscopy, x-ray photoemission spectroscopy, and density functional theory (DFT) calculations. Two types of APDBs form on each reconstruction; they consist of Ti$_x$O$_y$ vacancy clusters with a specific stoichiometry. The presence of these clusters is controlled by the oxygen pressure during annealing. The structural models of the vacancy clusters are resolved with DFT, which also shows that their relative stability depends on the chemical potential of oxygen. The surface band bending can be tuned by controlling the vacancy clusters at the domain boundaries.