Electronic structure of a Bi-doped Σ=13 tilt grain boundary in ZnO

We have investigated Bi doping in the bulk and in a Sigma = 13 tilt grain boundary in ZnO using ab-initio DFT-calculations. We obtain a negative segregation energy suggesting that bismuth accumulates in the grain boundary. The Bi-atom causes considerable atomic displacements in the grain boundary increasing the local Bi-O bond length and attracting an O-atom on the opposite side of the structural unit in the grain boundary. The results suggest the formation of a Bi-rich phase in the grain boundary. The Bi-atoms act as donors and the conduction electrons are quasi-localised in the grain boundary region.