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HL: Fachverband Halbleiterphysik

HL 7: Quantum dots: Optical properties I

HL 7.2: Vortrag

Montag, 23. März 2009, 13:45–14:00, BEY 118

InGaAs QDs on GaAs(111) substrate for entangled photon pairs — •Irina Ostapenko¹, Andrei Schliwa¹, Erik Stock¹, Sven Rodt¹, Vladimir Haisler², and Dieter Bimberg¹ — ¹IFP, TU Berlin — ²Institute of Semiconductor Physics, Novosibirsk, Russia

Quantum dots (QDs) are ideally suited for the generation of polarization-entangled photon pairs [1] that enable certain quantum cryptography protocols [2] and quantum teleportation [3]. However, even a small fine-structure splitting of the bright-exciton state may hinder the formation of such pairs based on the biexciton to exciton to vacuum recombination cascade. Our recent calculations [4] have revealed that growth of InGaAs QDs on GaAs(111) substrates leads to a vanishing fine-structure splitting. Here we expect a three-fold rotational symmetry in the growth plane and piezoelectric effects will not reduce the symmetry of the confining potential in contrast to QDs grown on GaAs(001) substrates [5]. We report on a successful approach to grow such QDs via droplet-mode MBE. Optical characterization is performed by cathodoluminescence and electroluminescence in combination with metal shadow masks. The results are compared to droplet-exiptaxy QDs on "standard" GaAs(001) substrates.

[1] O. Benson et al., Phys. Rev. Lett. 84, 2513 (2000)

[2] A. K. Ekert, Phys. Rev. Lett. 67, 661 (1991)

[3] T. Jennewein et al.,Phys. Rev. Lett. 88, 017903 (2002)

[4] A.Schliwa et al., Deutsche Patentanmeldung (2008)

[5] O.Stier et al., Phys. Rev. B 59, 8 (1999)