Influence of slab thickness on the Casimir force

We calculate the Casimir force between slabs of finite thickness made of intrinsic and doped silicon with different concentration of carriers and compare the results to those obtained for gold slabs. We use the Drude and the plasma models to describe the dielectric function for the carriers in doped Si. We discuss the possibility of experimentally testing the appropriateness of these models. We also investigate the influence of finite thickness on $VO_2$, which has recently been proposed for Casimir effect measurements testing the metal-insulator transition.