Interplay of Nb and Native Defects on the n‐Type Characteristics of Nb‐Doped SnO 2 : A Hybrid Functional Study

Nb‐doped SnO 2 with native defects has been systematically investigated using the Heyd–Scuseria–Ernzerhof (HSE) hybrid functional method, aiming at an in‐depth understanding of the interplay between native defects and Nb dopant, as well as the associated influences on the n‐type characteristics of Nb‐doped SnO 2 . First, we examine a Nb substitution for Sn (Nb Sn ) in a 3 × 3 × 5 SnO 2 supercell and find that the transition level of the substitutional Nb between the 1+ and neutral states lies within the conduction band, inducing n‐type conduction (the calculated electrical conductivity is in the order of 10 3 Ω −1 cm −1 ). Simultaneously, the Nb substitution does not destroy the optical transparency of SnO 2 , as it neither narrows the band gap nor introduces deep gap states, thereby accounting well for the experimentally observed n‐type transparent conductivity in Nb‐doped SnO 2 . Furthermore, the interplay between the Nb dopant and native defects is examined through introducing them into the above doped system. It is revealed that, compared to other defects, the oxygen vacancy ( V O ) preferentially coexists with Nb due to strong mutual attraction, leading to the formation of Nb‐ V O association. Such a dopant–defect complex drives the V O ‐induced localized charges (at the Sn atoms surrounding V O ) to disperse to the faraway Sn atoms, helping to preserve the n‐type characteristics of Nb‐doped SnO 2 . Efforts have been made to address the thermodynamic and kinetic stabilities of the Nb‐ V O complex in SnO 2 . This study provides valuable insights for a better understanding of the n‐type characteristics of Nb‐doped SnO 2 .