Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 36: Ge, GeSi, and Si
HL 36.6: Vortrag
Mittwoch, 24. März 2010, 10:45–11:00, H14
Transient optical gain in Germanium quantum wells — •Sangam Chatterjee1, Christoph Lange1, Niko S. Köster1, Martin Schäfer1, Mackillo Kira1, Stephan W. Koch1, Daniel Chrastina2, Giovanni Isella2, Hans von Känel2, and Hans Sigg3 — 1Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, Renthof 5, D 35032 Marburg, Germany — 2CNISM and L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo di Como, via Anzani 42, I-22100 Como, Italy — 3Laboratory for Micro and Nanotecnology, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
One of today’s most-sought goals in semiconductor technology is the monolithic integration of microelectronics and photonics on Si. Optical gain is, in general, not expected for Si and Ge or its alloys due to the indirect nature of the band gap in this material system. Here, we show that Ge/SiGe QWs show transient optical gain and may thus be used as an optically-pumped amplifier at room temperature [1]. Further, the nonequilibrium effects which govern the relaxation dynamics of the optically injected carrier distributions in this material were observed and analyzed using a microscopic many-body theory. Strong non-equilibrium gain was obtained on a sub-100 fs time scale. Long-lived gain arising from Γ-point transitions is overcompensated by a process bearing the character of free carrier absorption.
[1] C. Lange et al., Phys. Rev. B 79, 201306(R) (2009)