High-density InP self-assembled quantum dots embedded in In0.5Al0.5P grown by metalorganic chemical vapor deposition

We describe the characteristics of high-density InP self-assembled quantum dots embedded in ${\mathrm{In}}_{\mathrm{0.5}}{\mathrm{Al}}_{\mathrm{0.5}}\mathrm{P}$ cladding layers grown at 650 °C on GaAs (100) substrates by metalorganic chemical vapor deposition. Quantum dots grown with different deposition times are characterized by atomic force microscopy, photoluminescence, and transmission electron microscopy. For certain growth conditions, we observe the formation of a high density of quantum dots on the order of ${10}^{10} {\mathrm{cm}}^{\mathrm{-2}}.$ The quantum dot average height increases from ∼5 to ∼25 nm with deposition time, while the quantum dot density changes insignificantly. Photoluminescence (4 K) shows a gradual shift of emission spectral peak from 2.06 eV (for 7.5 ML) to 1.82 eV (for 22.5 ML), corresponding to changes in the dominant quantum dot size. Also, incoherent quantum dot formation is not observed for up to 15 ML growth.