Excitons formation from spatially separated electrons and holes in semiconductor nanostructures with disorder

We study the exciton formation in a disordered double layer semiconductor nanostructures in which electrons and holes are spatially separated by a potential barrier. To perform numerical simulations, we use the lattice gas model where the electron–hole system is divided into unit cells. We found that as the free carrier density increases the relative exciton density first increases rapidly and reaches a maximum value and then decreases slowly and eventually reaches a constant value. This phenomenon is associated with the presence of a random potential in the system. Our theory also predicts that disorder promotes the dissociation of excitons in double layer systems.