Regensburg 2013 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 1: Tutorial: Coherent Control

HL 1.4: Tutorium

Sonntag, 10. März 2013, 17:55–18:30, H2

Ultrafast coherent control of electrical currents in semiconductors and nanostructures — •Markus Betz — Experimentelle Physik 2, TU Dortmund

Current flow through semiconductor devices is usually achieved by applying potential differences to contacts. Over the last 15 years, however, also purely optical approaches to induce currents on the femtosecond timescale have been developed. Ultrabroadband light pulses - synthesized from a fundamental and its second harmonic - have proven particularly useful for such coherent control techniques. Current injection thereby relies on a quantum interference of one- and two-photon absorption pathways. The vectorial direction of the lateral current is dictated by the phase structure of the light field and its polarization. In my talk I will review the concept of coherent control of electrical currents in semiconductors. Starting from current injection in the prototypical direct semiconductor GaAs, we have extended the technique to the indirect bandgap materials silicon and germanium. Currents are also induced in single semiconductor nanostructures. In particular, we analyze optically induced currents in electrically contacted GaAs nanowires as well as hybrid structures functionalized with optical antennas. More recent experiments show up spectroscopic applications which conveniently combine the time resolution of ultrafast optics with amplitude- and phase-resolution of interferometric techniques.