Dresden 2006 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 7: Quantum dots and wires: Optical properties I

HL 7.9: Vortrag

Montag, 27. März 2006, 12:15–12:30, POT 151

Micro-photoluminescence investigations on single InGaN quantum dots up to 150 K — •K. Sebald, H. Lohmeyer, J. Gutowski, T. Yamaguchi, and D. Hommel — Institute of Solid State Physics, University of Bremen, Germany

To fully utilize the potential of InGaN quantum dot (QD) samples for future device applications their optical properties must be studied thoroughly. We will present micro-photoluminescence (µ-PL) measurements on single InGaN QDs. The QD samples were grown by MOVPE on sapphire (0001) substrates. The InGaN is deposited on a GaN buffer at a temperature of 700^∘C. The InGaN QD layer is stabilized by a novel kind of capping layer. For the final GaN capping the growth temperature is increased up to 820^∘C. Mesa structures with diameters down to 200 nm have been fabricated by focused-ion-beam etching after evaporation of an Al₂O₃ protection layer. Due to the low spatial surface density of the QDs one gets access to the optical properties of isolated QDs already at mesa diameters of 600 nm. The emission peaks possess linewidths down to 0.2 meV which is in the order of the spectral resolution of the experimental setup. µ-PL measurements on single InGaN QDs were carried out in dependence on the excitation density. We report on the observation of binding and antibinding multiexcitonic states. Furthermore, we were able to analyse the emission of single QDs up to 150 K and to quantify their activation energy.