Convertible Green Luminescence Determined by Surface Band Bending in ZnO

Green luminescence (GL) of ZnO is a typical defect emission and an important research topic for defect-controlling engineering. Two kinds of spectral characteristics, namely, Gaussian GL (GGL) and fine-structure GL (FSGL), are designated from a variety of spectra. It is found that GGL and FSGL can be reversibly converted through surface modification techniques where the location of the recombination center, the surface state, or the degree of band bending is modified. This convertible feature proves that the carrier recombination could be precisely controlled by surface modification. On the other hand, the effect of surface treatment on defects has achieved an unambiguous understanding, which is beneficial to effectively improve the performance of ZnO devices.