Hybrid Density Functional Study on the <i>p</i>-Type Conductivity Mechanism in Intrinsic Point Defects and Group V Element-Doped 2D β-TeO₂

The newly discovered two-dimensional (2D) β-TeO₂ possesses extraordinarily high <i>p</i>-type carrier mobility and demonstrates immense potential in the electronics field. However, current research on its <i>p</i>-type conductivity mechanisms and the modifications of element doping remains relatively insufficient. In this study, the intrinsic point defects and extrinsic element doping in monolayer β-TeO₂ are comprehensively analyzed to probe the potential sources of the intrinsic <i>p</i>-type conductivity and the extrinsic <i>p</i>-type doping possibility in 2D β-TeO₂ through hybrid density functional calculations. Our results reveal that the vacancy defects with low formation energies have deep transition levels and thus cannot be used as sources of unintentional <i>p</i>-type conductivity in 2D β-TeO₂. The investigations and discussions via Group V element doping modifications in 2D β-TeO₂ indicate that bismuth (Bi) doping can easily and significantly enhance the <i>p</i>-type conductivity of 2D β-TeO₂ under the presence of O-rich, which can be achieved experimentally. Furthermore, Bi doping can significantly increase carrier mobility without seriously affecting the electronic structure. The finding shows that the Bi element is an ideal dopant candidate for a <i>p</i>-type modification in 2D β-TeO₂. Our calculations pave an alternative strategy to achieve the realization of superior <i>p</i>-type conductivity in 2D β-TeO₂.