The evolution of the localized plasmon modes in a semi-infinite superlattice with cap layer

Using a transfer matrix method, we study the properties of the localized plasmon modes in a semi-infinite semiconductor superlattice (SL) with cap layer. The results show that in such a structure there exist three localized plasmon modes. They may appear either in the gap between two bulk plasmon bands, or below and above the bulk plasmon bands. The evolution from the extended plasmon modes to the localized plasmon modes can clearly be tracked with the change of the structural parameters or the relative electron density. A brief analysis of these results is given. It is suggested that the localized plasmon modes can be artificially controlled by adjusting the parameters of the proposed micro-structures.