The interest in single-photon-emitters rises continuously since quantum communication based on the polarization of single photons has already been demonstrated. Unfortunately up to now almost all single-photon sources are pumped optically which makes the realization of a widespread communication network very complex.

For this reason it would be of great advantage to fabricate electrically pumped single-photon-sources. This can be realized e. g. by fabricating LED structures with active regions, where only single ions are incorporated, leading to single photon emission. The LEDs could be driven electrically and the optical energy of the LED is transferred to the single transition available in the active region of the LED. Today, only very few reports on electrical single photon sources are available.

Zinc is a very promising candidate as a single photon emitter in GaN based LEDs. Zn acceptors show efficient emission in the blue spectral range. Zn creates a deep acceptor level 0.3 eV – 0.4 eV above the valence band. Furthermore, Silicon-codoping is required for efficient optical emission, resulting in a very bright photo-luminescence at 2.9 eV (~ 430 nm) which has been assigned to donor-acceptor (DA) transitions.

The goal of this thesis is to investigate single transitions in GaN based LEDs with Zn and Si co-doping. LEDs will be fabricated by MOCVD and processed in house. A thorough analysis of the relevant optical transitions by time resolved optical characterization will allow to get information on the nature and characteristics of the transitions, as well as on the emission statistics in order to get a quantitative handle on the statistical quality of single photon emission correlated with that.

Scholarship Application Deadline: 31 March 2011

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