As the active dimensions of metal-oxide field-effect transistors are approaching the atomic scale, the electronic properties of these "nanowire" devices must be treated on a quantum mechanical level. In this paper, the transmission coefficients and the density of states of biased and unbiased Si and GaAs nanowires are simulated using the sp 3 d 5 s * empirical tight-binding method. Each atom, as well as the connections to its nearest neighbors, is represented explicitly. The material parameters are optimized to reproduce bulk band-structure characteristics in various crystal directions and various strain conditions. A scattering boundary method to calculate the open boundary conditions in nanowire transistors is developed to reduce the computational burden. Existing methods such as iterative or generalized eigenvalue problem approaches are significantly more expensive than the transport simulation through the device. The algorithm can be coupled to nonequilibrium Green's function and wave function transport calculations. The speed improvement is even larger if the wire transport direction is different from ͓100͔. Finally, it is demonstrated that strain effects can be easily included in the present nanowire simulations.

An analytical model of the band gap narrowing (BGN) in silicon was derived from a non-self-consistent finite-temperature full random-phase approximation (RPA) formalism. Exchange-correlation self-energy of the free carriers and correlation energy of the carrier-dopant interaction were treated on an equal basis. The dispersive quasi-particle shift (QPS) in RPA quality was numerically calculated for a broad range of densities and temperatures. The dispersion was found to be smooth enough for the relevant energies to justify the rigid shift approximation in accordance with the non-self-consistent scheme. A pronounced temperature effect of the BGN only exists in the intermediate density range. The contribution of the ionic part of the QPS to the total BGN decreases from 1/3 at low densities to about 1/4 at very high densities. Based on the numerical results, Padé approximations in terms of carrier densities, doping, and temperature with an accuracy of 1 meV were constructed using limiting cases. The analytical expression for the ionic part had to be modified for device application to account for depletion zones. The model shows a reasonable agreement with certain photoluminescence data and good agreement with recently revised electrical measurements, in particular for p-type silicon. The change of BGN profiles in a bipolar transistor under increasing carrier injection is demonstrated.

A framework is proposed that allows for a joint description and optimization of both binary polar coding and 2 m -ary digital pulse-amplitude modulation (PAM) schemes such as multilevel coding (MLC) and bit-interleaved coded modulation (BICM). The conceptual equivalence of polar coding and multilevel coding is pointed out in detail. Based on a novel characterization of the channel polarization phenomenon, rules for the optimal choice of the labeling in coded modulation schemes employing polar codes are developed. Simulation results regarding the error performance of the proposed schemes on the AWGN channel are included.All authors are with the

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We have established a simulation model for phosphorus-doped silicon emitters using Fermi-Dirac statistics. Our model is based on a set of independently measured material parameters and on quantum mechanical calculations. In contrast to commonly applied models, which use Boltzmann statistics and apparent band-gap narrowing data, we use Fermi-Dirac statistics and theoretically derived band shifts, and therefore we account for the degeneracy effects on a physically sounder basis. This leads to unprecedented consistency and precision even at very high dopant densities. We also derive the hole surface recombination velocity parameter S po by applying our model to a broad range of measurements of the emitter saturation current density. Despite small differences in oxide quality among various laboratories, S po generally increases for all of them in a very similar manner at high surface doping densities N surf. Pyramidal texturing generally increases S po by a factor of five. The frequently used forming gas anneal lowers S po mainly in low-doped emitters, while an aluminum anneal ͑Al deposit followed by a heat cycle͒ lowers S po at all N surf .