Growth and characterization of polar (0001) and semipolar (11−22) InGaN/GaN quantum dots

We report a comparison of the plasma-assisted MBE growth of polar (0001) and semipolar (11−22)-oriented InGaN/GaN quantum dots (QDs) grown simultaneously on GaN templates. The photoluminescence (PL) from semipolar QDs shows a systematical blueshift in comparison to the respective polar samples. Notwithstanding the variation in the internal electric field between the two samples, the observed shift in the PL spectrum can be attributed to the different In incorporation in the two crystallographic orientations. The evolution of PL intensity with temperature confirms the three-dimensional carrier confinement, which results in an attenuation of nonradiative recombination effects in comparison with quantum well structures.