The role played by Pr-doping in double Schottky barrier formation at single grain boundaries was investigated by using a combination of current-voltage measurements, atomic-resolution Z-contrast scanning transmission electron microscopy and first-principles calculations. Although Pr segregated to the specific atomic site along boundaries, it was found not to be the direct cause of non-linear current-voltage properties. Under suitable annealing conditions, Pr instead enhanced the formation of acceptor-type native defects that were essential for the creation of double Schottky barriers in ZnO.

Role of Pr Segregation in Acceptor-State Formation at ZnO Grain Boundaries. Sato, Y., Buban, J.P., Mizoguchi, T., Shibata, N., Yodogawa, M., Yamamoto, T., Ikuhara, Y.: Physical Review Letters, 2006, 97[10], 106802