Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 31: Quantenpunkte und -dr
ähte: Herstellung und Charakterisierung
HL 31.8: Vortrag
Mittwoch, 26. März 2003, 16:15–16:30, BEY/154
Impact of the Sb-surfactant on the Monolayer Splitting of the InAs Quantum Dot height — •Konstantin Pötschke1, L. Müller-Kirsch1, R. Heitz1, R. L. Sellin1, U. W. Pohl1, D. Bimberg1, N. Zakharov2, and P. Werner2 — 1Inst. für Festkörperphysik, TU Berlin, Hardenbergstr. 36, 10623 Berlin — 2MPI für Mikrostrukturphysik, Weidenstr. 2, 06289 Halle
InAs/GaAs quantum dots (QDs) have been grown using trimethylindium and the alternative precursor tertiarybuthylarsin at low V/III ratios. At these growth conditions up to five distinguishable peaks are observed in photoluminescence measurements at 10 K and low excitation densities. The peaks originate from a multimodal distribution of the QD ground state transition energy. The modulation is attributed to monolayer variations of the QD height, indicating well defined planar upper and lower interfaces. Eight-band k·p calculations show that the observed behavior requires a low aspect ratio in good agreement with TEM results. The island formation can be followed varying the growth interruption after depositing the quantum dot layer. The QDs with larger aspect ratios grow in volume and height on the cost of the flatter quantum dots with increasing duration of the growth interruption. Changing the gas phase by offering antimony during the growth interruption broadens the size distribution and up to eight peaks are observed. Higher and larger QDs form, resulting in a red shift of the photoluminescence on the low energy side. The change of the multimodal distribution is discussed in view of antimony acting as surfactant, changing the surface energy and therefore the QD formation.