Design of annealing conditions for the formation of isolated single-photon emitters at SiO2/SiC interfaces

Density control of color centers is crucial to suppress the overlap between their luminescence and make them individually function as single-photon emitters (SPEs). In the present study, we studied the impact of post-oxidation annealing conditions on the formation of highly bright and isolated SPEs at the SiO2/SiC interface. The results showed that CO2 annealing reduces the color centers more rapidly than Ar annealing and forms spatially separated bright spots. The bright spot density was reduced from 7.4 × 107 to 5.6 × 105 cm−2 by CO2 annealing at 1200 °C for 15 min, while Ar annealing in the same condition resulted in comparatively higher density (6.0 × 106 cm−2). Thus, in addition to a purely thermal effect, a reaction involving CO2 molecules is responsible for controlling the density of bright spots in a wide range. Through Hanbury-Brown and Twiss measurements, we found that 90% of the bright spots investigated in the 15 min CO2 annealed sample showed g(2)(0) values below 0.5 and served as SPEs. The results highlight the importance of properly designing the post-oxidation annealing conditions to spatially separate the color centers and allow them to function as SPEs.