Fabrication and photoluminescence of quantum dots induced by strain of self-organized stressors

Quantum dots have been fabricated from InGaAs/GaAs quantum wells by growing self-organized InP islands on the surface of the structure. The strain from the island-stressors modifies locally the band edges of the quantum well, forming quantum dots. The deposition conditions of InP are optimized to ensure a narrow size distribution of InP islands with a density of about IO⁹ cm^-2 measured by atomic force microscopy. The lateral strain-induced confinement of carriers produces distinct energy levels as seen in photoluminescence measurements. The ground state transition is redshifted by 64-105 meV from the quantum well peak, depending on the top barrier thickness. Five narrow excited state transitions separated by up to 19 meV are observed between the ground state peak and the quantum well peak at increasing excitation intensity. The narrow linewidth and high photoluminescence efficiency of the dots indicates the very high optical quality of the structure.