A nearly universal critical conductivity for semiconductor-metal alloys

Abstract

Classical ionized impurity scattering is employed to calculate the conductivity at and in the vicinity of the critical point. The result sigma(iis)(x = x(c),T) = Asqrt[T], closely given by e(2)/Planck's over 2pilambda(dB) with the de Broglie wavelength lambda(dB) = h/(2m(*)kT)(1/2) in the nondegenerate regime epsilon(F)<<kT, is weakly dependent on the form of the density of states above the mobility edge. This result can explain the sqrt[T] term observed for amorphous semiconductor alloys. sigma(iis)(x>x(c), T) might also explain the linear scaling behavior sigma(x, T)-Asqrt[T] = sigma(0)(x/x(0)-1).