Stranski-Krastanov growth of InGaN quantum dots

InGaN based devices with high Indium content suffer from inhomogeneities and high defect densities. InGaN quantum dots (QD) have the opportunity to overcome these drawbacks and could realize green light emitting diodes and laser diodes. We have investigated the growth of capped and uncapped InGaN QDs on GaN templates by metal organic vapor epitaxy (MOVPE). For uncapped InGaN samples with increasing InGaN thickness and Indium contents above 20% a growth mode transition from 2D to 3D occurs, i.e. Stranski-Krastanov growth mode. The density of QDs increases with increasing amount of InGaN beyond the wetting layer. As the indium content is increased the wetting layer thickness is reduced. All InGaN layers up to 6 nm are fully strained with indium content from 20% to 30%. Overgrowth at low temperature obtains the InGaN QDs. However, overgrowth at higher temperature increases the Indium diffusion and change the QD morphology.