Effects of growth interruption on the structural and optical properties of GaN self-assembled quantum dots

Abstract

ABSTRACTWe report the effects of thermal annealing and growth interruption on the formation of GaN self-assembled quantum dots (QDs) grown by low-pressure metalorganic chemical vapor deposition (MOCVD). For the uncapped QD structures, atomic force microscopy (AFM) analysis shows that the density of the QDs rapidly increases and then decreases with increasing the annealing time. This is due to the combined effect of the QD formation process and the ripening process. The size of the QDs increases with increasing the annealing time. We have also investigated the photoluminescence (PL) property of the AlN capped QD structures with different growth interruption times. The PL from the QDs showed a red-shift with increasing the growth interruption time. In contrast, the PL from the wetting layer (WL) shows a blue-shift. These results indicate that the formation of the QDs is proceeding at the expense of the WL, which is consistent with the AFM analysis of the thermal annealing effect. These results show that the growth interruption plays an important role in the formation of the QDs.