Excitonic States Of Gan/Algan Quantum Well Structures Under High Density Of Excitation

Photoluminescence of GaN/AlGaN quantum well structures was studied under high intensity of excitation. The blue shift of photoluminescence peak energy was observed when excitation intensity increased. The blue shift was most prominent for the wide wells, becoming smaller with decreasing the well width. We attribute the observed effect to the screening of the built-in electric field by photoexcited carriers, which leads to reducing of the initial red shift caused by the quantum confined Stark effect. The variation of exciton binding energy with carrier concentration also makes the contribution to the blue shift. The theoretical calculations of the blue shift were performed and compared with experimental data.