Room-temperature photoluminescence (PL) measurements are performed on GaInN/GaN multiple-quantum-well heterostructures grown on GaN-on-sapphire templates with different threading-dislocation densities. The selective optical excitation of quantum wells and the dependence of integrated PL intensity on excitation power allow us to determine the internal quantum efficiency (IQE) as a function of carrier concentration. The measured IQE of the sample with the lowest dislocation density (5.3×108 cm−2) is as high as 64%. The measured nonradiative coefficient A varies from 6×107 to 2×108 s−1 as the dislocation density increases from 5.3×108 to 5.7×109 cm−2, respectively.

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