Exploring Intrinsic\nand Extrinsic <i>p</i>‑Type Dopability of Atomically\nThin β‑TeO<sub>2</sub> from First Principles

Two-dimensional (2D) β-TeO<sub>2</sub> has gained\nattention\nas a promising material for optoelectronic and power device applications,\nthanks to its transparency and high hole mobility. However, the mechanisms\ndriving its <i>p</i>-type conductivity and dopability remain\nelusive. In this study, we investigate the intrinsic and extrinsic\npoint defects in monolayer and bilayer β-TeO<sub>2</sub>, the\nlatter of which has been experimentally synthesized, using the Heyd–Scuseria–Ernzerhof\n(HSE) + D3 hybrid functional. Our results reveal that most intrinsic\ndefects are unlikely to contribute to <i>p</i>-type doping\nin 2D β-TeO<sub>2</sub>. Moreover, Si and H contamination could\nfurther impair <i>p</i>-type conductivity. Since the point\ndefects do not contribute to <i>p</i>-type conductivity,\nwe suggest two possible mechanisms for hole conduction: hopping conduction\nvia localized impurity states, and substrate effects. We also explored\nsubstitutional <i>p</i>-type doping in 2D β-TeO<sub>2</sub> with 10 trivalent elements. Among these, the Bi dopant is\nfound to exhibit a relatively shallow acceptor transition level. However,\n all the dopants introduce deep localized states, where hole polarons\nare trapped by the lone pairs of Te atoms. Interestingly, monolayer\nβ-TeO<sub>2</sub> shows potential advantages over bilayers due\nto reduced self-compensation effects for <i>p</i>-type dopants.\nThese findings provide valuable insights into defect engineering strategies\nfor future electronic applications involving 2D β-TeO<sub>2</sub>.