| We study electrostatic screening of external point charges by semi-infinite semi-conductors, and electrostatic screening of external charge distributions, screening of static, uniform electric fields and screening of excess charges by small semiconductors and non-ideal metallic systems such as spherical nanoclusters and carbon nanotubes. The equilibrium properties of the above systems, such as electrostatic potentials, electric fields, screening charge distributions, static polarizability, self-capacitance and charging energy are obtained employing linearized Thomas-Fermi (Debye-Hückel) approximation.; We further study steady-state transport of electron and hole photocarriers, generated in pairs by low-intensity light at an ideal, uncharged surface of semi-infinite, non-degenerate semiconductor. Starting from the first principles of irreversible thermodynamics, we obtain transport equations (i.e. carrier fluxes and recombination rates) in terms of carrier electrochemical potentials. This approach enables us to satisfy explicitly the non-equilibriurn entropy production requirements as well as requirement of the system overall, rather than local electroneutrality (quasi-neutrality). The approach is then employed in studying the Dember effect, for two physically distinct cases: (1) in intrinsic or weakly doped systems, where the change in ionized impurity number densities, if present, due to the carrier recombination on the impurity sites is negligible; (2) in systems doped so that the change in ionized impurity number densities due to the carrier recombination is not negligible.; At the end, the application of the approach is outlined for three-carrier systems such as semiconductors with spin polarized carriers, widely employed in spintronics. |
