Bulk and surface collective excitations of electron hole plasma in semiconductor superlattices with zero valence band offset

Abstract

We study bulk and surface collective excitations in a semiconductor superlattice with a very large conduction band offset and a negligible valence band offset. The electron-hole plasma is modelled by an array of quasi two-dimensional electron gas layers and a uniform, homogeneous hole gas. It is found that a gap opens in the high frequency plasmon spectrum, that the dispersion and Landau damping of acoustical plasmons is highly anisotropic and varies strongly with the mass ratio of carriers. The surface plasmons show strong wavevector dependence but can be found below the bulk plasmon band for very small wave vectors.