The Role of Nitrogen Dopants in ZnO Nanoparticle-Based Light Emitting Diodes

In this work, nitrogen-doped ZnO nanoparticles were synthesized in various conditions by the gas evaporation method with DC arc plasma. Nitrogen concentrations of 6.38 × 10¹⁸ cm^-3 to 2.6 × 10¹⁹ cm^-3 were obtained at a chamber pressure of 150 torr, using arc currents of 20 A to 70 A. The intensities of local vibrational modes at 275 cm^-1 and 581 cm^-1 in the Raman spectra of ZnO nanoparticles showed a dependency on the nitrogen concentration in the ZnO nanoparticles. The ratios of donor-acceptor pair and exciton emissions in the photoluminescence spectra of nitrogen-doped ZnO nanoparticles, and the electroluminescence of light-emitting diodes based on these nanoparticles, were nearly proportional to the Raman peak's intensity at 275 cm^-1. The results indicated that the nitrogen dopants in the ZnO nanoparticles were acting as an acceptor.