Controlling the carrier lifetime of nearly threading-dislocation-free ZnO homoepitaxial films by 3d transition-metal doping

Carrier lifetime in nearly threading-dislocation-free ZnOhomoepitaxial films was controlled by doping 3d transition-metals (TMs), Ni and Mn. The photoluminescence lifetime of the near-band-edge emission (τPL) was decreased linearly by increasing TM concentration, indicating that such TMs are predominant nonradiative recombination centers (NRCs). From this relationship, exciton capture-cross-section () of 2.4 × 10−15 cm2 is obtained. Because of native-NRCs (Zn-vacancy complexes) is likely larger than this value, the linear dependence of the internal quantum efficiency on τPL observed in our TM-doped ZnO and unintentionally dopedZnO in literatures indicates that the concentrations of native-NRCs in the latter are “lower than” 1016–1017 cm−3