Metallization of ZnO nanowires from partial hydrogen adsorption

First-principle density functional calculations of [0001] ZnO nanowires demonstrate that exposure of the mixed-terminated {01 (1) over bar0} side surfaces to atomic hydrogen can result in drastic changes of electronic properties. When the dangling bonds of the side surfaces are completely saturated by H atoms, the nanowires are insulating, with band gaps much higher than that of bulk solid. In contrast, the ZnO nanowires with only O atoms saturated by atomic H on the side surfaces are metallic. The physical mechanism for the remarkable changes is discussed. These theoretical results suggest a new way of band engineering ZnO nanowires.