Effects of line defects on the electronic properties of ZnO nanoribbons and sheets

We perform a comprehensive study of the effects of different types of line defects on the electronic and magnetic properties of ZnO nanoribbons and monolayer sheets by using first-principles computations. Our computations show that for zigzag ZnO nanoribbons, their metallic characteristics are unchanged by the line defects, although certain nanoribbons can exhibit much higher magnetic moments contributed by atoms within the line defects. For the armchair nanoribbons containing the 4-8 line defects, their semiconducting characteristics are the same as those of the defect-free nanoribbons. Besides the line defects, two large-angle grain boundaries are also considered for zigzag and armchair nanoribbons. In both cases, the ZnO nanoribbons show metallic characteristics. Finally, the effects of line defects on 2D ZnO monolayer sheets are also studied. It is found that the line defects in ZnO sheets can markedly enhance visible-light absorption.