Confinement effects in strain-induced InGaAs/GaAs quantum dots

The effects of both lateral and vertical confinements in strain-induced InGaAs/GaAs quantum dots were investigated by varying the InP stressor size, the width and composition of the quantum well as well as the GaAs caplayer thickness. The energy-level spacing decreases with increasing the stressor diameter and very large stressor leads to a barrel-shaped lateral confining potential rather than a parabolic one. The hydrostatic strain along the central axis of the stressor decays exponentially with a characteristic depth of about 25 nm. The quantum-dot state energies can be tuned easily by the quantum-well width and composition. If the QW is thin or the indium composition is small, the quantum dot states may be leaky due to weak vertical confinement.