Stranski-Krastanov GaN∕AlN quantum dots grown by metal organic vapor phase epitaxy

We report a thorough study of the growth of self-assembled $\mathrm{Ga}\mathrm{N}∕\mathrm{Al}\mathrm{N}$ quantum dots (QDs). These QDs were grown on sapphire substrates using the Stranski-Krastanov (SK) growth mode by means of low-pressure metal organic vapor phase epitaxy. The influence of the V∕III ratio on the QD height, shape, and density is studied. Emissions above $\left(3.8\mathrm{eV}\right)$ and below $\left(2.8\mathrm{eV}\right)$ the band gap of GaN are observed for small dots $\left(1.3\mathrm{nm}\right)$ and large ones $\left(4.4\mathrm{nm}\right)$ , respectively. Special emphasis was given to the SK growth mode transition and the parameters influencing the QD formation. The two-dimensional–three-dimensional transition is studied continuously by photoluminescence mapping showing its high sensitivity to the V∕III ratio.