Electronic structure of self-assembled InAs quantum dots in InP: An anisotropic quantum-dot system

The electronic structure of self-assembled InAs quantum dots embedded in an InP matrix has been investigated using Fourier-transform infrared spectroscopy and capacitance spectroscopy. We observe a splitting of about 25 meV between the conduction-band excited states. We argue that this is likely to be a consequence of a strong anisotropy in the lateral size of the dots. Furthermore, we observe a replica in the absorption spectrum, shifted by about 160 meV from the fundamental, which we attribute to an excited heavy-hole state. The InAs/InP dots can be well described in a simple adiabatic approach with a hard quantum well-like potential for the vertical confinement and a soft anisotropic harmonic potential for the lateral confinement.