Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 24: Thermoelectricity

HL 24.6: Talk

Tuesday, March 17, 2015, 10:45–11:00, EW 202

Thermoelectric properties of n-doped Silicon and simple metals from first-principles — •Mattia Fiorentini and Nicola Bonini — King's College London, Strand, London, United Kingdom

Understanding transport phenomena is a key task to design and engineer materials for thermoelectric and nano-electronic applications. Despite the extensive activity in the field, the state-of-the-art still lacks a comprehensive first-principles numerical framework to tackle the problem. Here we present a computational infrastructure to calculate the electronic transport coefficients of bulk systems within the Boltzmann transport equation (BTE) formalism. The electronic and vibrational properties, including the electron-phonon interaction, are computed using Density Functional theory and Density Functional Perturbation theory. We exploit the Wannier interpolation to efficiently sample fine grids in reciprocal space. The linearized BTE is solved exactly using a Conjugate Gradient algorithm. Our method goes beyond the standard practice, which relies upon various flavors of the relaxation-time approximation and uses semi-empirical models of carriers' dispersions and interactions. Here we study the thermoelectric properties of n-doped Silicon and Copper in a wide range of temperatures. Our results are in good agreement with the experimental observations and elucidate the relative importance of the various scattering mechanisms in the different regimes. For Copper, we give an explanation for the anomalous behavior of the Seebeck coefficient. As an additional outcome, we assess the accuracy of simplified models and approximations that are commonly used to study transport in semiconductors.