Electronic Properties and Mid-Infrared Transitions in Self-Assembled Quantum Dots

We present a detailed model of the electronic properties of single and vertically aligned self-assembled pyramidal InAs/GaAs quantum dots (SADs) which is based on the self-consistent solution of three-dimensional (3D) Poisson and Schroedinger equations within the local (spin) density approximation. Nonparabolicity of the band structure and a continuum model for strain between GaAs and InAs results in position and energy dependent effective mass. In single SADs, shell structures obeying Hund's rule for various occupation numbers in the pyramids agree well with recent capacitance measurements. The electronic spectra of SADs of various shapes have been determined with intraband level transitions and mid-infrared optical matrix elements. In the case of two vertically aligned pyramidal SADs, we show that quantum mechanical coupling alone between identical dots underestimates the magnitude of the coupling between the dots, which in large part is due to piezoelectricity and size difference between SADs.