GENERAL-MODEL OF THE TRANSVERSE DIELECTRIC-CONSTANT OF GAAS-ALAS SUPERLATTICES

The presented model is based on treating separately the individual contributions from the GAMMA , X, and L valleys, enabling us to understand better the general trends of the overall dielectric constant. An accurate k multiplied by (times) p band calculation is used to determine the bulk band structure around the three symmetry points and a realistic Kronig-Penney model is used to calculate the influence of the superlattice periodicity on the bulk band structure. The resulting dielectric constant shows a small polarization effect due to the anisotropy of the superstructure and a large amount of fine structure corresponding to different transitions between the quantized levels. The influence of the barrier and well thicknesses, L//B and L//Z, respectively, is also important and it is shown that for a constant value of x OVER BAR equals L//B/(L//B plus L//Z), the real part of the zero frequency dielectric constant increases as a function of L//B.