Fabrication of quantum emitters in aluminum nitride by Al-ion implantation and thermal annealing

Single-photon emitters (SPEs) within wide-bandgap materials represent an appealing platform for the development of single-photon sources operating at room temperatures. Group III-nitrides have previously been shown to host efficient SPEs, which are attributed to deep energy levels within the large bandgap of the material, in a configuration that is similar to extensively investigated color centers in diamond. Antibunched emission from defect centers within gallium nitride and aluminum nitride (AlN) have been recently demonstrated. While such emitters are particularly interesting due to the compatibility of III-nitrides with cleanroom processes, the nature of such defects and the optimal conditions for forming them are not fully understood. Here, we investigate Al implantation on a commercial AlN epilayer through subsequent steps of thermal annealing and confocal microscopy measurements. We observe a fluence-dependent increase in the density of the emitters, resulting in the creation of ensembles at the maximum implantation fluence. Annealing at 600 C results in the optimal yield in SPEs formation at the maximum fluence, while a significant reduction in SPE density is observed at lower fluences. These findings suggest that the mechanism of vacancy formation plays a key role in the creation of the emitters and open enticing perspectives in the defect engineering of SPEs in solid state.