Determinants of the structured and structureless green emissions of ZnO

Green emission can be identified as either a structured or a structureless emission. In the downward surface band bending region, the influence of defects on the continuous change in the 0–0 electronic transition was found to be a dominating factor that differentiates the characteristics of green emission. Such a change in the 0–0 electronic transition gives rise to the structureless green emission at higher energy, while the 0–0 electronic transition in the bulk of ZnO plays an important role resulting in structured green emission with lower energy.