Impact of formation process on the radiation properties of single-photon sources generated on SiC crystal surfaces

Abstract

Radiation centers that are generated on the surface of SiC crystals [surface single-photon sources (SPSs)] have received much attention because they behave as high-brightness SPSs at room temperature. However, little is known about surface SPSs, such as their defect structure and radiation properties. To achieve a better understanding of surface SPSs, we investigated the impact of the formation processes of SPSs on the radiation properties. Low temperature photoluminescence (PL) measurements indicated that the photon energies of the zero-phonon line (ZPL) were dispersed in the range of 0.33 eV. In comparison between the (0001) Si-face and (11–20) a-face, the energy dispersion for the a-face was smaller, which suggests that the energy dispersion was attributed to stacking faults at the oxide–SiC interface. The differences in the radiation properties of the surface SPSs were clarified according to the formation process in terms of the oxide thickness and post-oxidation Ar annealing. The results showed that the wavelength dispersion was increased with the oxide thickness, and Ar annealing caused various changes in the radiation properties, such as a reduction in the density of SPSs, and the radiation intensity of the ZPL as well as a shift in the ZPL wavelength. Notably, most of the changes in the defect structure occurred at the Ar anneal temperature of 600 °C, and we discuss some of the types of defects that change at this temperature.