Plasma densities and conductivities of semiconductor surfaces

Owing to charge in surface states, a curvature of the energy bands occurs near the surface inside a semiconductor. The shape of the curvature has been calculated, with the approximation that the impurities are fully ionised and the free-carrier distribution is nondegenerate. The results permit the calculation of the plasma-density distribution near the surface and the conductivity variation. It is shown that the conductivity varies to such an extent that bulk values cannot be taken for the computation of the microwave skin depth in semiconductors.