In unbiased non-centrosymmetric semiconductors electronic currents can be excited on ultrashort time scales using purely optical excitation. A combined approach of k.p-perturbation theory and the semiconductor Bloch equations can be used to theoretical describe these photocurrents in bulk and quantum well systems. Including the Coulomb interaction and resulting excitonic effects is a very challenging task due to the large numerical requirements. Here, we present a non-standard grid which significantly reduces the numerical requirements while still ensuring converged results. We analyze and compare the convergence behavior of standard Cartesian and geodesic grids for shift current simulations and present results on the enhancement of the shift current by the excitonic resonance in bulk GaAs which are based on an anisotropic three-dimensional k.p band structure.
Reinold Podzimski, Huynh Thanh Duc, and Torsten Meier, "A microscopic approach to ultrafast near band gap photocurrents in bulk semiconductors," Proc. SPIE 10102, Ultrafast Phenomena and Nanophotonics XXI, 101020P (Presented at SPIE OPTO: January 31, 2017; Published: 23 February 2017); https://doi.org/10.1117/12.2250299.
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