Growth of InAlAs self-assembled quantum dots on InAlGaAs/InP for 1.55 μm laser applications by metalorganic chemical vapor deposition

We report on the growth of InAlAs self-assembled quantum dots or simply (QDs) on In_0.53(Al_0.5Ga_0.5)_0.47As matrices lattice matched on InP (001) substrates using metal organic chemical vapor deposition. We found that (1) a small amount of aluminum strongly affects the morphology of the InAlAs QDs, (2) using a long growth interruption (∼140–190 s) before the growth of the QDs is an important element in QD formation, and (3) the AsH₃ flow rate during the growth of QDs are very important to get high-quality and high-density QDs on the InAlGaAs surface. A bimodal size distribution of InAlAs QDs is found at low growth temperatures. However, when raising the QD growth temperature, the density of “big” InAlAs QDs becomes lower while the density of “small” QDs becomes much higher. Eventually, a high-density (∼5.1×10¹⁰ cm^-2) unimodal size distribution of In_0.92Al_0.08As QDs with emission around λ∼1.55 μm is realized at the optimized growth temperature condition. The QDs and the In_0.53(Al_0.5Ga_0.5)_0.47As barrier are grown at the same temperature of 650 °C.