A Theoretical Analysis of Sb~(5+) Incorporation in Highly Doped SnO_2 Matrix

摘要

We have used the periodic quantum-mechanical method with density functional theory at the B3LYP hybrid functional level in order to study the doping of SnO_2 with pentavalent Sb~(5+). The 72-atom 2x3x2 supercell SnO_2 (Sn_(24)O_(48)) was employed in the calculations. For the SnO2:4%Sb, one atom of Sn was replaced by one Sb atom. For the SnO2:8%Sb, two atoms of Sn were replaced by two Sb atoms. The Sb doping leads to an enhancement in the electrical conductivity of this material, because these ions substitute Sn~(4+) in the SnO_2 matrix, leading to an electronic density rise in the conduction band, due to the donor-like behavior of the doping atom. This result shows that the bandgap magnitude depends on the doping concentration, because the energy value found for SnO_2:4%Sb was 2.8eV whereas for SnO_2:8%Sb it was 2.7eV. It was also verified that the difference between the Fermi level and the bottom of the conduction band is directly related to the doping concentration.