Photodynamics of Ga_Zn-V_Zn complex defect in Ga-doped ZnO

The wide-band-gap II-VI compound semiconductor ZnO is regarded as a promising single-photon emission (SPE) host material. In this work, we demonstrate that a (Ga_Zn-V_Zn)^- complex defect can readily be obtained and the density can be controlled in a certain range. In analogy to nitrogen vacancy centers, such a defect in ZnO is expected to be a new single photon source. The optical properties of the (Ga_Zn-V_Zn)^- complex defect are further studied by photoluminescence and time-resolved photoluminescence spectra measurements. The electron transitions between the defect levels emit light at~650 nm with a lifetime of 10-20 nanoseconds, indicating a good coherent length for SPE. Finally, a two-level emitter structure is proposed to explain the carrier dynamics. We believe that the photodynamics study of the (Ga_Zn-V_Zn)^- complex defect in this work is important for ZnO-based quantum emitters.