Published online by Cambridge University Press: 01 February 2011
We report a photoluminescence study of near-surface GaN/AlN superlattices grown by metalorganic chemical vapor deposition (MOCVD) on a thick GaN layer. Undoped, Si-doped and Mg-doped structures with the well/barrier thickness ratio 3:1 and different periods are investigated. It is found that the energy position, intensity and linewidth of the emission are determined by the interplay of the built-in polarization field, depletion field and screening by the free carriers. In n-type structures an electron accumulation at the bottom interface is evidenced by the observed recombination of the two-electron gas with the photo-excited holes.