Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 36: Quantenpunkte und -dr
ähte: Optische Eigenschaften I

HL 36.8: Vortrag

Donnerstag, 11. März 2004, 12:00–12:15, H17

Microphotoluminescence studies on CdSe/Zn(S,Se) quantum dots and InGaN/GaN structures — •H. Lohmeyer, K. Sebald, J. Gutowski, S. Einfeldt, and D. Hommel — Institut für Festkörperphysik, Universität Bremen, Otto-Hahn-Allee, 28359 Bremen

The use of quantum dots (QD) as active medium promises laser structures with superior properties in comparison to conventional quantum-well lasers, especially with respect to the threshold current. A systematic optical characterization with high spatial resolution is indispensable for the realization of such new devices and is possible by means of microphotoluminescence (µ-PL) measurements. We present µ-PL results for two material systems emitting in the green and blue spectral range.

To get access to few or even single QDs, mesa structures with diameters down to 120 nm were etched out of the investigated self-organized grown CdSe/Zn(S,Se)-QD sample. The µ-PL spectra of a 120 nm mesa-structure shows clearly separated excitonic emission lines. Additionally, these excitonic states were characterized by µ-PL excitation spectroscopy and time resolved measurements. As a result the spectrally broad optical phonon replica and the first excited state of the exciton have been identified. The recombination time of the excitonic state is determined to 230 ps, which is independent of the excitation density.

Furthermore first µ-PL results of InGaN/GaN samples with respect to the identification of characteristic QD luminescence are discussed.