Is p-Type Doping in TeO2 Feasible?

Abstract Wide-bandgap two-dimensional (2D) β-TeO 2 has been reported as a high-mobility p -type transparent semiconductor ( Nat. Electron . 2021 , 4 , 277-283), attracting significant attention. This “breakthrough” not only challenges the conventional characterization of TeO 2 as an insulator but also conflicts with the anticipated difficulty in hole doping of TeO 2 by established chemical trends. Notably, the reported Fermi level of 0.9 eV above the valence band maximum actually suggests that the material is an insulator, contradicting the high hole density obtained by Hall effect measurement. Furthermore, the detected residual Se and the possible reduced elemental Te in the 2D β-TeO 2 samples introduces complexity, considering that elemental Se, Te, and Te 1- x Se x themselves are high-mobility p -type semiconductors. Therefore, doubts regarding the true cause of the p -type conductivity observed in the 2D β-TeO 2 samples arise. In this Letter, we employ density functional theory calculations to illustrate that TeO 2 , whether in its bulk forms of α-, β-, or γ-TeO 2 , or in the 2D β-TeO 2 nanosheets, inherently exhibits insulating properties and poses challenges in carrier doping due to its shallow conduction band minimum and deep valence band maximum. Our findings shed light on the insulating properties and doping difficulty of TeO 2 , contrasting with the claimed p -type conductivity in the 2D β-TeO 2 samples, prompting inquiries into the true origin of the p -type conductivity.