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.