Regensburg 2007 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 31: Quantum dots and wires: Optical properties III

HL 31.12: Talk

Wednesday, March 28, 2007, 17:45–18:00, H17

Single InGaAs Quantum Dots Embedded in Electrically Active Photonic Crystal Nanocavities — •Felix Hofbauer, Michael Kaniber, Max Bichler, Gerhard Böhm, Gerhard Abstreiter, and Jonathan Finley — Walter Schottky Institut, Am Coulombwall 3, TU München, 85748 Garching, Germany

We present investigations of the coupling of single InGaAs quantum dots (QDs) to both extended and strongly localised optical modes in electrical contacted 2D photonic crystal (PC) nanostructures. The samples investigated consist of an 180nm thick, free-standing GaAs membrane into which a PC is formed by etching a triangular lattice of air holes. Low mode-volume (V < (λ /n)³) and high-Q (∼ 2000) cavities are introduced by single missing hole defects. Embedding the QDs into the intrinsic region of a p-i-n diode enables us to apply static electric fields to QDs in the cavity and control the energy detuning between the dot and cavity using the quantum confined Stark effect.

The active PC nanocavities were studied using spatially resolved luminescence and photocurrent absorption spectroscopy. Quenching of the PL is observed for fields >50 kV/cm due to carrier tunneling escape from the dots that occurs over timescales faster than the radiative lifetime. By measuring the PL quenching as a function of position on the PC and nanocavity we electrically probe the local density of photonic states via a shift of the threshold voltage. Also investigations of the exciton lifetime and PL intensity of single QDs as a function of spectral detuning from the cavity mode are made.

Supported financially via Sonderforschungsbereich-631