Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 70: Quantum Dots and Wires: Theory

HL 70.2: Talk

Thursday, March 17, 2011, 10:30–10:45, POT 151

Electronic properties of (111)-grown InGaAs/GaAs quantum dots — •Oliver Marquardt and Eoin O’Reilly — Tyndall National Institute, Lee Maltings, Cork, Ireland

InGaAs-QDs grown along the (111)-axis in GaAs exhibit electronic properties that are excellently suited to the generation of single and entangled photons, as required for quantum cryptography or quantum computing purposes.

We employ an eight-band k·p model to provide a theoretical study of these nanostructures. Strain and polarisation potentials that modify the bulk electronic properties of the system are calculated using second-order continuum elasticity theory. Moreover, we have taken second-order piezoelectric contributions into account in our calculations of the polarisation potential.

Our studies reveal that, for the case of (111)-grown zincblende InGaAs/GaAs quantum dots, second-order piezoelectric contributions have a significant influence on electron and hole eigenenergies and charge densities. In particular, such second-order contributions are found to significantly reduce the resulting polarisation potentials in comparison to potentials obtained from using only the first-oder piezoelectric constants. This reduction of the piezoelectric potential allows for better electron-hole overlap and thus higher recombination rates and is in much better agreement with recent experimental observations than calculations employing first-order piezoelectric constants only.