Electroluminescence from n-Mn doped ZnO/n-GaN heterojunction light-emitting diodes

A Mn doped ZnO (MZO) film was prepared on n-GaN coated sapphire substrate, followed by post-deposition annealing at 700 °C, thus an n-n heterojunction light-emitting diode (LED) was fabricated, and red electroluminescence (EL) at a low voltage was realized. The n-MZO/n-GaN heterojunction shows a rectification ratio of ~ 2.0 × 10⁵ at ± 2 V and a dark current of 3.5 nA at -2 V. The n-MZO/n-GaN heterojunction LED displays a strong red electroluminescence with the threshold voltage of about 4.6 V. The dominant mechanism of EL is ascribed to the formation of the substitutional Mn in the interior of the MZO film annealed at a high temperature, and the formation of the MnZnGaO blocking layer during the annealing process is another potential factor.