Oxygen Vacancies in the Single Layer of Ti2CO2 MXene: Effects of Gating Voltage, Mechanical Strain, and Atomic Impurities

Abstract

Herein, using first‐principles calculations the structural and electronic properties of the Ti2CO2 MXene monolayer with and without oxygen vacancies are systematically investigated with different defect concentrations and patterns, including partial, linear, local, and hexagonal types. The Ti2CO2 monolayer is found to be a semiconductor with a bandgap of 0.35 eV. The introduction of oxygen vacancies tends to increase the bandgap and leads to electronic phase transitions from nonmagnetic semiconductors to half‐metals. Moreover, the semiconducting characteristic of O‐vacancy Ti2CO2 can be adjusted via electric fields, strain, and F‐atom substitution. In particular, an electric field can be used to alter the nonmagnetic semiconductor of O‐vacancy Ti2CO2 into a magnetic one or into a half‐metal, whereas the electronic phase transition from a semiconductor to metal can be achieved by applying strain and F‐atom substitution. The results provide a useful guide for practical applications of O‐vacancy Ti2CO2 monolayers in nanoelectronic and spinstronic nanodevices.