High-density and uniform-size GaN/Al0.5GaN self-assembled quantum dots grown by metalorganic chemical vapor deposition

Self-assembled GaN/Al0.5GaN quantum dots (QDs) were grown on a c-plane sapphire by Stranski- Krastanov (S-K) mode in metalorganic vapor-phase epitaxy (MOCVD). The growth window for GaN QDs by S-K is very narrow owing to the small lattice mismatch (1.25%) of the GaN/Al0.5GaN. In this work, we find that the growth duration and growth interruption possess distinct and regular effects on the size and density of GaN/Al0.5GaN QDs, which can be utilized as growth optimization windows. In the end, the uniform-size GaN QDs with a density of 1.7×1010 cm-2 are achieved. A strong PL peak at 3.36eV originated from the uncapped GaN/Al0.5GaN QDs is observed, compared with the peak at 4.5eV assigned to the underlying Al0.5GaN template.