Superlattice formed by quantum-dot sheets: Density of states and infrared absorption

Low-energy continuous states of electron in a heterosrtucture with periodically placed quantum-dot sheets are studied theoretically. The Green's function of an electron is governed by the Dyson equation with the self-energy function which is determined the boundary conditions at quantum-dot sheets with weak damping in the low-energy region. The parameters of a superlattice formed by quantum-dot sheets are determined using the short-range model of quantum dot. The density of states and spectral dependencies of the anisotropic absorption coefficient under midinfrared transitions from doped quantum dots into miniband states of a superlattice strongly depend on dot concentration and on the period of sheets. These dependencies can be used for the characterization of the multilayer structure and they determine the parameters of different optoelectronic devices exploiting the vertical transport of carriers through quantum-dot sheets.