Effect of roughness on the conductivity of semiconducting thin films/quantum wells with double rough boundaries

We have investigated the influence of surface/interface roughness on the electrical conductivity in semiconducting thin films/quantum wells with double self-affine rough interface boundaries. The self-affine boundary roughness is characterized by the roughness exponent H, the in-plane correlation length ξ, and the rms amplitude Δ. In addition, nonzero cross correlation between the interfaces are taken into account during the conductivity calculations. The latter is shown to affect strongly the electrical conductivity. Nevertheless, the exact effect depends strongly on the values of the interface correlation lengths and roughness exponents. Finally, the ratio between conductivities slightly below and above the critical thickness for which the second miniband is occupied is shown to be strongly sensitive on the form of the correlation function (or the interface roughness exponents), and the presence of cross correlations.