Dots-in-NANOWires by near-field illumination: novel single-photon sources for HYbRid quantum photonic circuits

ongoing

Quantum photonic integrated circuits are ideal platforms for quantum computation and communication. A long-standing issue in their realization is the lack of a deterministic quantum light source compatible with silicon. Indeed, planar self-assembled III-V quantum dots (QDs) –which provide high-performance quantum light sources (i. e. single photons)– can hardly be grown on Si, and also lack the positioning control necessary for efficient post-growth III-V-on-Si hybrid integration. Nanowires (NWs), in contrast, are rod-shaped nanoscale semiconductors that can host intrinsically site-controlled III-V QDs and can even be grown on Si. However, QDs in NWs have yet to reach the performances of planar QDs, an issue that could be overcome by integrating QDs in NWs in photonic cavities. Such a solution is, at present, out of reach, because conventional creation of QDs during NW growth hinders their successful integration with cavities. The NANOWHYR project will allow the integration of QDs in NWs with cavities by realizing an unprecedented post-growth creation of QDs inside NWs. The new method consists of the incorporation of hydrogen in III-V nitride NWs whose bandgap can be controllably modified by hydrogen. Subsequent hydrogen removal by scanning near-field illumination will permit tuning the bandgap of the NW in a nanoscale region. This will allow us to form a QD in that region with a widely tunable energy. The deterministic control of the QD position and energy is the key that will enable us to efficiently integrate the QD with: A) planar photonic cavities fabricated on Si and B) vertical NW cavities grown on Si. This will lead to the breakthrough of a site-controlled, electrically-driven, telecom-friendly single photon source in Si photonic circuits. Moreover, this new strategy permits the modulation of semiconductor properties at the nanoscale, and it is thus expected to open new grounds in other research areas, such as photovoltaics and thermal energy converters.