The Dopant Local Effect on the Stability of an Oxygen Vacancy and the Reliability of a Conductive Filament in Rutile Titanium Dioxide

Abstract

Metal doping has long been recognized as a general strategy to modify electronic properties of semiconductors. The purpose here is to understand the behavior of oxygen vacancy when existing together with a metal dopant in rutile TiO2 through first‐principles calculation. For the coexistence of an oxygen vacancy and an Ag/Hf dopant, the dopant local effect determines that the formation energy of the oxygen vacancy depends on distances from it to the Ag/Hf dopant. Increased formation energy of an oxygen vacancy adjacent to an Ag dopant is attributed to the fact that the holes produced because of lower valence of Ag than Ti are filled by electrons left by the oxygen vacancy. The same valence of Hf as Ti results in that the electrostatic repulsive force pushes the Hf dopant outward from nearby oxygen vacancy, which lowers the formation energy of the oxygen vacancy. Furthermore, oxygen vacancies coexisting with an Ag/Hf dopant are of interest for investigating the effect of metal doping on the reliability of conductive filaments. The Hf dopant adjacent to the oxygen vacancies greatly enhances the strength of a conductive filament. The built‐in electric fields from localized electrons are considered as the seed action of metal doping in resistive switching devices.