Formation of quantum dots with post-growth thermal annealing of InGaN/GaN quantum wells

It is shown that post-growth thermal annealing of such a sample with temperature ranging from 800 to 900 °C led to a better confinement of indium rich clusters near InGaN quantum well layers. Transmission electron microcopy (TEM) and energy filter TEM results manifested that the sizes of indium-rich QDs were reduced with increasing annealing temperature. Also, the size homogeneity was improved. Quasi-regular arrays of indium-rich QDs embedded in InGaN quantum wells were observed in the sample of 900 °C annealing. X-ray diffraction also showed the enhancement of InN relative intensity. Photoluminescence measurements revealed blue shifts of photon emission spectral peak, indicating stronger quantum confinement after thermal annealing.