  We have investigated the combined effect of low-energy self-implantation and
thermal annealing on the near-surface defect concentration of ZnO
single-crystals. Using ionoluminescence (IL), we demonstrate that a combination
of low-energy low-fluence Zn and O ion implantation followed by annealing in Ar
increases the near-surface point defect concentration in ZnO by two orders of
magnitude. Point defects are known to increase the surface reactivity of ZnO,
thereby improving the efficiency of ZnO photocatalytic processes such as
bilirubin degredation. We hereby provide recommendations on how to improve the
efficiency of ZnO-related photocatalytic processes.
