Luminescence, structure and aging c-axis - Oriented silver doped ZnO nanocrystalline films

The analysis has shown that the location of Ag-acceptor levels in ZnO is still unclear. To identify Ag related defects the emission, structure and aging process have been studied in the silver doped ZnO nanocrystalline films obtained by the ultrasonic spray pyrolysis with different Ag concentrations within of 1-4 at%. It is revealed that at low Ag doping (1-2 at%) the ZnO crystal structure improves, but the higher (3-4 at%) Ag content leads to crystal lattice disordering. The bright emission related to Ag doping with PL peaks at 2.68 and 2.97 eV at 10 K have been detected in PL spectra of ZnO:Ag films at 2-3 at% Ag. At higher Ag content (≥ 3 at%) the PL intensity of majority PL bands falls down together with the formation of metallic Ag inclusions in ZnO:Ag films. At aging ZnO:Ag films the intensities of PL bands (2.68 and 2.97 eV) fall down, but the intensity of orange PL band increases. The study of PL temperature dependences permits to analyze the nature of emitting defects responsible for the blue (2.68 and 2.97 eV), green and orange PL bands. The transformation of emitting defects at aging has been discussed.