Plasmons in aperiodic structures

We study and compare plasmon spectra in semiconductor superlattices with periodic, quasiperiodic (e.g., Fibonacci sequence), and random spacings. Novel mode structures are found in the quasiperiodic cases, particularly for low values of level broadening that arises from inherent disorder effects. We discuss critically the observability of this novel mode structure via light scattering studies in experimentally realizable superlattices. In addition, our results suggest that the finite Fibonacci-sequence superlattice may be considered as a partially ordered-layer lattice with no long-range positional order, but with strong short-range order, since our calculated plasmon spectra exhibit very little difference between the finite Fibonacci sequence and the periodic abaab superlattice.