Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 3: Heterostructures

HL 3.6: Vortrag

Montag, 23. März 2009, 11:45–12:00, BEY 154

High-Quality AlGaAs/GaAs Quantum Well-Microcavities for Exciton-Polariton Studies — •Arash Rahimi-Iman¹, Georgius Roumpus², Christian Schneider¹, Sven Höfling¹, Stephan Reitzenstein¹, Alfred Forchel¹, and Yoshihisa Yamamoto² — ¹Technische Physik, Universität Würzburg, D-97074 Würzburg, Germany — ²E. L. Ginzton Laboratory, Stanford University, Stanford, CA 94305-4088, USA

In a semiconductor microcavity with embedded quantum wells (QWs) new eigenmodes are formed called the polaritons when the confined cavity photon modes strongly couple to the QW excitons. Cavity polaritons and their ability to undergo Bose-Einstein condensation have been intensively studied in the last decade. As quasiparticles in semiconductors, polaritons have typically relatively short lifetimes, thus it is generally difficult to cool hot polaritons to the lattice temperature before they decay. Significantly higher polariton lifetimes would allow further progress in this field, e.g., the generation of a condensate in thermal equilibrium featuring macroscopic coherence.

We report on the observation of polaritons in an optically pumped planar high-quality (high-Q) AlGaAs/GaAs microcavity containing 12 GaAs QWs in a 3/2 λ AlAs cavity sandwiched between a lower and an upper distributed Bragg reflector with 32 and 36 mirror pairs, respectively. Moreover, time resolved photoluminescence from the lower polariton branch was measured with a streak camera in order to estimate the photon lifetime τ_ph and the Q-factor of the cavity, respectively. Thereby, a Q-factor of >10,000 was determined for cavity photons.