Quasiregular quantum-dot-like structure formation with postgrowth thermal annealing of InGaN/GaN quantum wells

Postgrowth thermal annealing of an InGaN/GaN quantum-well sample with a medium level of nominal indium content (19%) was conducted. From the analyses of high-resolution transmission electron microscopy and energy filter transmission electron microscopy, it was found that thermal annealing at 900 °C led to a quasiregular quantum-dot-like structure. However, such a structure was destroyed when the annealing temperature was raised to 950 °C. Temperature-dependent photoluminescence (PL) measurements showed quite consistent results. Blueshift of the PL peak position and narrowing of the PL spectral width after thermal annealing were observed.