Photoluminescence and recombination mechanisms in GaN/Al0.2Ga0.8N superlattice

A detailed study of photoluminescence (PL) of GaN(1 nm)/Al0.2Ga0.8N(3.3 nm) twenty periods superlattice grown via metal-organic chemical vapor deposit ion is presented. The dependence of the PL emission energy, linewidth, and intensity on temperature, in the low temperature regime, is consistent with recombination mechanisms involving bandtail states attributed to a small d egree of interfacial disorder. The activation energy of the nonradiative ce nters in our superlattice agrees well with the value we derive for the widt h of the tail-state distribution. Moreover, we find that the average phonon energy of the phonons that control the interband PL energy at high tempera tures is larger for the superlattice than for a high-quality GaN film. This observation is consistent with model calculations predicting the phonon mo de properties of GaN-AlN-based wurtzite heterostructures. (C) 2000 American Institute of Physics. [S0003-6951(00)00915-3].