Electronic structure evolution and quantum transport mechanism in F-doped SnO₂ thin films: a first-principles study

The effects of F doping concentration on the electronic structure and transport properties of SnO₂ were systematically investigated using density functional theory (DFT) combined with the nonequilibrium Green's function (NEGF) method. The results show that F doping effectively modulates the electronic structure of SnO₂, with the band gap decreasing from 2.56 eV for pristine SnO₂ to 1.96 eV at 8.33% F doping, indicating enhanced n-type characteristics. Charge density and Bader charge analyses reveal that F substitution induces significant charge redistribution and enhances charge transfer within the lattice. Electronic transport calculations demonstrate that moderate F doping increases the density of states and transmission probability near the Fermi level, resulting in improved conductance and current response. In contrast, excessive F doping suppresses electron transmission and deteriorates transport performance. Real-space transmission-eigenchannel and inverse participation ratio analyses further indicate that this transport suppression is accompanied by enhanced localization of the dominant transport channel at high F concentrations. Among all investigated structures, the Au-SnO₂-Au device with approximately 7.50% F doping exhibits the highest conductance and the most favorable transport characteristics under the present computational model. These findings demonstrate that F doping is an effective strategy for tuning the electronic structure and transport behavior of SnO₂ and provide theoretical guidance for the design and optimization of high-performance SnO₂-based electronic and optoelectronic devices.