Biexciton emission strongly enhanced by plasmonic nano-cone

Semiconductor quantum dots (Q-dots) are desirable in many applications because they can emit multiple photons for each excitation pulse via the generation of multiple excitons. In practice, however, multi excitonic emissions are hampered by fast non radiative decay-channels such as Auger recombination. By making use oft he large radiative enhancement in the near-field of a gold nano-cone antenna,we have demonstrated a significant improvement in Q-dot biexciton emission efficiency. The nano-cone was fabricated by focused ion beam milling and a single Q-dot was positioned in its near-field with nanometer accuracy using scanning probe technology. A careful and thorough measurement of the fluorescence emission rate, lifetime, and second-order autocorrelation function, at various excitation powers and separations between the Q-dot and the nano-cone, allowed us to determine a radiative enhancement factor of about 100 for both the excitonic and biexcitonic emission channels. This resulted in more than an order of magnitude improvement in biexciton emission efficiency. The findings are in good agreement with theoretical calculations, which suggest that the current enhancement factors are limited by the finite size of the Q-dot.

Strong plasmonic enhancement of biexciton emission: controlled coupling of a single quantum dot to a gold nanocone antenna
K. Matsuzaki, S. Vassant, H.-W. Liu, A. Dutschke, B. Hoffmann, X. Chen, S. Christiansen, M. R. Buck, J. A. Hollingsworth, S. Götzinger, and V. Sandoghdar
Scientific Reports 7, 42307, (2017)