Nitrid-basierte Einzelphotonenquellen mit optischen Resonatoren

Im Fokus dieses Teilprojektes stehen blau und UV emittierende GaN-basierte VCSEL-Strukturen. Mit einer analogenepitaktischen Schichtfolge können durch Adaption des photonic crystal bandgap (PBC) Konzepts hochbrillante Kantenlaserrealisiert werden. Insbesondere die große Bandlücke und hohe Exzitonenbindungs-energie in GaN eröffnen neue Perspektivenfür starke Licht-Materie-Kopplung, Polaritonen-Laser, Bose-Einstein-Kondensation und insbesondere Einzel- verschränktePhotonenemission bei Raumtemperatur. Die in GaAs bereits erfolgreich realisierten Konzepte sollen auf die breitbandigen Gruppe-III-Nitride übertragen werden.

Nitride-based resonant cavity single photon sources

Nitride based single photon sources (SPS) for room temperature operation will be fabricated and characterized in this project. A novel approach based on position controlled single GaN/AlN quantum dots (QD) grown by MOVPE inside resonant cavity structures is pursued. Currently, GaN QDs are fabricated either by strained-layer epitaxy, by nanowire growth or by selective area growth [1-3]. In established device fabrication technologies planar surfaces, as usually maintained during strained-layer epitaxy of GaN QDs, are preferable to the 3D surface structures resulting from other approaches. However, nucleation sites of GaN QDs in the self-assembling, planar approach occur at non-predictable random positions and are largely affected by the presence of dislocation networks. We want to overcome this limitation using a nitride-based buried stressor technology that introduces a considerable in-plane stress component at predefined positions at the growth surface of QDs adopting the successful approach of A2 from the arsenide system to the nitrides. We will therefore develop a well controlled selective lateral oxidation process following an approach by [4] to create a nitride-based buried stressor structure on AlN templates. The impact of such stressors on QD nucleation within a dislocation-rich environment will be studied, particularly making use of the nano-scale resolution of our unique (S)TEM-CL characterization facilities. A technology for single-photon emitter devices will be developed including monolithically-integrated optical elements such as mirrors and resonant microcavity structures as well as micro lenses for enhanced light extraction.
Electronic quantum dot states based on GaN/AlN provide optical transitions (intraband transitions) in telecom-munication regions at 1.3 and 1.55 μm wavelength an alternative approach to realize SPS for fiber-based secure data communication. For the first time, we will explore fundamental properties of such transitions for generating single photons.