Dresden 2003 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 49: Poster II
HL 49.82: Poster
Donnerstag, 27. März 2003, 16:30–19:00, HSZ/P2
Manipulating the Electronic Coupling Between Vertically Correlated InGaAs-GaAs Quantum Dots — •Hubert krenner1, Jonathan Finley1, Evelin Beham1, Max Bichler1, Gerhard Abstreiter1, and Artur Zrenner2 — 1Walter Schottky Institut, Technische Universität München, 85748-Garching — 2Universität Paderborn, 33098 Paderborn
We present the results of an extensive growth study of pairs of vertically correlated self-assembled InGaAs quantum dots (QDs) separated by thin GaAs spacers. Our results demonstrate that the electronic structure of the two QD-layers (QD1-lower, QD2-upper) can be manipulated via modification of the InGaAs coverage for the upper QD layer and the In-Ga ratio. By reducing the nominal InGaAs coverage for QD2 from 100%-75% of the value used for QD1 whilst maintaining a constant spacer thickness (7nm), we observed a systematic blue-shift of the photoluminscence (PL) of QD2 and an increased spectral overlap with the PL from QD1. In addition, a strongly systematic variation of the QD-emission wavelength (up to ∼120nm) was found as the In-As ratio was varied. Based on these studies, we have optimised the growth parameters for coupled InGaAs QDs to maximise the interdot electronic coupling. The electronic coupling between the QDs was controllably manipulated via incorpoaration into Schottky photodiodes. As the axial electric field was varied, a satellite PL peak (RS) emerged the amplitude of which resonates over a narrow range of electric field. This feature is identified as arising from the bonding-like coupled electronic state. Good agreement between these observations and recent theoretical predictions is found.