Theoretical investigation of collective excitations in HgTe/CdTe superlattices. I. Intrasubband excitation.

Abstract

In this paper, we study in detail the electron collective excitations of HgTe/CdTe superlattices with a simple model superlattice, taking into account the overlap of wave functions at the interfaces for interface states. The linear-response theory has been used with success to calculate the density response of the superlattice to an external perturbation, including many-body effects and electron\char21{}heavy-hole coupling in a reasonable way for intrasubband modes. Some attractive features are found compared with those in type-I and -II superlattices, such as, localized modulated three-dimensional optical and acoustical plasmons, and so on. Moreover, the coupling of interface states with heavy-hole-like subbands is discussed. Also, a comparison of the collective excitation spectra between the quasi-two-dimensional and purely two-dimensional charge interfaces, along with a discussion on their relevance to experiment, is presented.