Impact of radiation-induced defects on the yellow luminescence band in MOCVD GaN

Changes in a yellow luminescence band at similar to 2.2 eV were studied for n- and p-GaN subjected to electron and gamma-irradiation at room temperature. The intensity of the band strongly increases upon irradiation. Pronounced shifts of the band after irradiation is also observed. The experimental results obtained allow us to conclude that the gallium vacancy is involved in the yellow luminescence, in accordance with the recent theoretical predictions. It has been suggested that there is also another component in the luminescence band due to unidentified grown-in defects. Irradiation gives rise to strong changes in concentrations of charge carriers in n- and p-GaN.