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HL: Halbleiterphysik

HL 9: Poster I

HL 9.66: Poster

Montag, 27. März 2006, 15:15–17:45, P3

Indirect transitions and direct current in semiconductor superlattices generated by application of half-cycle pulses — •Andrey Moskalenko, Alex Matos-Abiague, and Jamal Berakdar — Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle, Germany

We investigate the action of a single half-cycle pulse (HCP) on a semiconductor superlattice. As a model system we choose a superlattice consisting of a lattice of delta function peaks. We calculate matrix elements for transitions between eigenstates of the superlattice and use them to calculate populations in minibands and charge current induced by the HCP having a duration that is short enough. The current consists of an intraminiband part, which is constant in time (neglecting the relaxation), and an oscillating interminiband part. We investigate the dependence of the intraminiband current on the strength of the HCP for different fillings of the lowest miniband at zero temperatures. We show that for a low filling of the lowest miniband the dependence of the intraminiband current on the strength of the HCP has minima when the wave vector transferred by the pulse to the carriers matches an integer of the half of the reciprocal lattice constant. In the case of the filled lowest miniband the dependence of the intraminiband current on the pulse strength has a threshold since for the generation of the intraminiband current the population in the second or higher minibands must be created.