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DDC: 510 × Subject: semiconductors ×

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Now showing 1 - 5 of 5
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    Challenges for drift-diffusion simulations of semiconductors: A comparative study of different discretization philosophies
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2018) Farrell, Patricio; Peschka, Dirk
    We analyze and benchmark the error and the convergence order of finite difference, finite-element as well as Voronoi finite-volume discretization schemes for the drift-diffusion equations describing charge transport in bulk semiconductor devices. Three common challenges, that can corrupt the precision of numerical solutions, will be discussed: boundary layers at Ohmic contacts, discontinuties in the doping profile, and corner singularities in L-shaped domains. The influence on the order of convergence is assessed for each computational challenge and the different discretization schemes. Additionally, we provide an analysis of the inner boundary layer asymptotics near Ohmic contacts to support our observations.
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    Some properties of the kinetic equation for electron transport in semiconductors
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2013) Wagner, Wolfgang
    The paper studies the kinetic equation for electron transport in semiconductors. New formulas for the heat generation rate are derived by analyzing the basic scattering mechanisms. In addition, properties of the steady state distribution are discussed and possible extensions of the deviational particle Monte Carlo method to the area of electron transport are proposed.
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    Optimal control of elastic vector-valued AllenCahn variational inequalities
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2013) Farshbaf-Shaker, Mohammad Hassan; Hecht, Claudia
    In this paper we consider a elastic vector-valued AllenCahn MPCC (Mathematical Programs with Complementarity Constraints) problem. We use a regularization approach to get the optimality system for the subproblems. By passing to the limit in the optimality conditions for the regularized subproblems, we derive certain generalized first-order necessary optimality conditions for the original problem.
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    Properties of the steady state distribution of electrons in semiconductors
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2010) Muscato, Orazio; Wagner, Wolfgang; Di Stefano, Vincenza
    This paper studies a Boltzmann transport equation with several electron-phonon scattering mechanisms, which describes the charge transport in semiconductors. The electric field is coupled to the electron distribution function via Poisson's equation. Both the parabolic and the quasi-parabolic band approximations are considered. The steady state behaviour of the electron distribution function is investigated by a Monte Carlo algorithm. More precisely, several nonlinear functionals of the solution are calculated that quantify the deviation of the steady state from a Maxwellian distribution with respect to the wave-vector. On the one hand, the numerical results illustrate known theoretical statements about the steady state and indicate possible directions for future studies. On the other hand, the nonlinear functionals provide tools that can be used in the framework of Monte Carlo algorithms for detecting regions in which the steady state distribution has a relatively simple structure, thus providing a basis for domain decomposition methods
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    Simulations and analysis of beam quality improvement in spatially modulated broad area edge-emitting devices
    (Berlin : Weierstraß-Institut für Angewandte Analysis und Stochastik, 2014) Radziunas, Mindaugas; Herrero, Ramon; Botey, Muriel; Staliunas, Kestutis
    We simulate and analyze how beam quality improves while being amplified in edge emitting broad area semiconductor amplifiers with a periodic structuring of the electrical contacts, in both longitudinal and lateral directions. A spatio-temporal traveling wave model is used for simulations of the dynamics and nonlinear interactions of the optical fields, induced polarizations and carrier density. In the case of small beam amplification, the optical field can be expanded into few Bloch modes, so that the system is described by a set of ODEs for the evolution of the mode amplitudes. The analysis of such model provides a deep understanding of the impact of the different parameters on amplification and on spatial (angular) filtering of the beam. It is shown that under realistic parameters the twodimensional modulation of the current can lead not only to a significant reduction of the emission divergence, but also to an additional amplification of the emitted field.