Density-density correlation functions and plasmons in tunnelling semiconductor superlattices

Abstract

The authors have studied the density-density correlation functions and plasmons in tunnelling semiconductor superlattices in the random-phase approximation, taking account of the overlap of the wavefunctions between adjacent quantum wells. Using the tight-binding wavefunctions, the electron-electron interaction and the density operator can be written as series of separable factors in matrix forms. The density-density correlation function can be explicitly expressed in a form consisting of multiplied matrices, and the plasmon dispersion relations are obtained. The crossover from 2D to 3D is shown.