Thermal Annealing Effects on the Photoluminescence of InGaN/GaN Quantum Wells

Thermal annealing effects on the photoluminescence characteristics of InGaN/GaN quantum wells grown by metalorganic chemical vapor deposition were investigated. The emission peaks of the InGaN/GaN quantum wells are red-shifted by conventional thermal annealing. The red-shift behavior of the photoluminescence peak energy is more prominent in samples grown at low temperatures. After a repetitive rapid thermal annealing, the red-shift behavior is observed even for InGaN/GaN quantum well samples grown at high temperatures. The activation energy of localized excitons increases from 110 meV to 153 meV with increasing number of repetitive rapid thermal annealing cycles. These abnormal red-shift behaviors in InGaN/GaN quantum wells due to thermal annealing are understood by both dislocation-mediated indium interdiffusion and strain relaxation of pseudomorphically grown InGaN/GaN quantum wells.