Contributions of $\hbox {N}^{+}$ , $\hbox {N}_{2}^{+}$ ,

Different nitrogen sources, pure N₂, pure NO, and NO mixed with O₂ (25% NO + 75% O₂), are used to confirm the effects of N⁺, N₂⁺, and NO⁺ ion implantation on the p-type conversion of ZnO:Al (AZO) films by plasma-immersion ion implantation (PIII) based on N-Al codoping mechanism. For the plasma of N₂, NO, and NO mixed with O₂, the major implanted ions are, respectively, N₂⁺ ions, N₂⁺ mixed with NO⁺ ions, as well as N⁺ mixed with O⁺ ions, confirmed by the optical emission spectra of plasma. After activation by postimplanted annealing, the photoluminescence and X-ray photoelectron spectroscopy analyses indicate that the implanted N⁺, N₂⁺, and NO⁺ ions replace the O sites and form nitrogen atom substitutions at O sites [(N_O)], nitrogen molecule substitutions at O sites [(N₂)_O], as well as zinc nitrite and zinc nitrate, respectively. Among all the N-induced defects, only N_O contribute to the p-type conversion of ZnO films. That explains why p-type conversion is only successfully achieved by NO mixed with O₂, while others still remain n-type conductivity. The mechanism of p-type conversion by N₂, NO, and NO mixed O₂ PIII was investigated in this paper.