Effect of barrier thickness on strain balanced InAs/GaAs QD solar cells

The effect of the thickness of the barrier layers between quantum dots (QD) in a vertically stacked QD array has been studied using both simulation and experimental techniques. Silvaco ATLAS is used to model how QW barrier thickness affects the onset of confined electron wavefunction overlap. This indicates that barrier thicknesses of less than 8 nm provide miniband formation between wells. P-i-n devices with a strain balanced QD/barrier superlattice embedded i-region were grown epitaxially with varying barrier thicknesses. Electroluminescence measurements were performed on the samples and the energy levels were determined. An overall redshift was observed as the barrier thickness between QD layers was decreased. This correlates well with the current understanding and recent modeling of these systems.