Open Access Nano Review

Experimental methods of post-growth tuning of the excitonic fine structure splitting in semiconductor quantum dots

Johannes D Plumhof*, Rinaldo Trotta, Armando Rastelli and Oliver G Schmidt

Author Affiliations

Institute for Integrative Nanosciences, IFW, Dresden, Helmholtzstr. 20, D-01069 Dresden, Germany

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Nanoscale Research Letters 2012, 7:336  doi:10.1186/1556-276X-7-336

Published: 22 June 2012

Abstract

Deterministic sources of polarization entangled photon pairs on demand are considered as important building blocks for quantum communication technology. It has been demonstrated that semiconductor quantum dots (QDs), which exhibit a sufficiently small excitonic fine structure splitting (FSS) can be used as triggered, on-chip sources of polarization entangled photon pairs. As-grown QDs usually do not have the required values of the FSS, making the availability of post-growth tuning techniques highly desired. This article reviews the effect of different post-growth treatments and external fields on the FSS such as thermal annealing, magnetic fields, the optical Stark effect, electric fields, and anisotropic stress. As a consequence of the tuning of the FSS, for some tuning techniques a rotation of the polarization of the emitted light is observed. The joint modification of polarization orientation and FSS can be described by an anticrossing of the bright excitonic states.

Keywords:
Semiconductor quantum dots; Excitonic fine structure splitting; Anticrossing; Entangled photon pairs