Ab initio calculations of the effect of N, Nb, and Ta doping on the electronic structure and optical properties of SnO2

Nanostructured nitrogen-, niobium-, and tantalum-doped tin oxides are investigated by first-principle calculations. First, the band structure, bond length, density of states, and projected density of states of pure tin oxide are evaluated. Then, the effect of nitrogen, niobium, and tantalum doping substituting O and Sn is compared with the pure case. In all cases, substitutional doping with N results in p -type conductivity whereas n -type conductivity results from Nb and Ta doping. Substitution of O with N and of Sn with Nb or Ta increases the bandgap of the structure, while substitution of Sn and Nb with N reduces the bandgap.