The growth of Mg-doped GaN thin films by metalorganic chemical vapor deposition (MOCVD) using NH3 and Cp2Mg as a source of nitrogen
and Mg, respectively, usually produces Mg–H complexes, which hinder the activation of Mg as shallow acceptor centers. Therefore, postgrowth treatments are commonly required to activate these acceptor centers. The presence of Mg dopants in GaN films induces various defectrelated emissions whose characteristics depend on the growth method. For this study, we prepared Mg-doped GaN thin films by plasmaassisted MOCVD. A nitrogen-plasma, instead of NH3, served as a nitrogen source to minimize the formation of Mg–H complexes, thereby
eliminating the requirement for post-growth treatment. The emission characteristics were obtained by measuring the photoluminescence of
the as-grown room-temperature films. Yellow, green, blue, and ultraviolet emission bands are produced by Mg-doped samples with different
Mg concentrations produced by Cp2Mg flow rates of 2%, 5%, and 10% of the total flow rate. Low-Mg concentration leads to nitrogen and
gallium vacancies, which results in yellow photoluminescence. At higher Mg concentration, the yellow photoluminescence is suppressed and
the blue photoluminescence is enhanced because of the incorporation of vacancies by Mg atoms. The analysis of the photoluminescence
spectra leads to the proposed band diagrams for Mg-doped GaN with varying Mg concentration.