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Spin defects of which states can be manipulated in Silicon Carbide (SiC) have drawn considerable attention because of their applications to quantum technologies. The single negatively-charged pairs of VSi and nitrogen atom (N) on an adjacent C site (NcVsi- center) in SiC is suitable for them. This paper reports the formation of NcVsi- centers on 4H-SiC epilayers with different nitrogen concentrations using light/heavy ion irradiation and subsequent thermal annealing. The formation of NcVsi- centers is characterized by the near infrared photoluminescence (PL) spectroscopy. It is shown that the PL intensity from NcVsi- centers depends on the N concentration and the ion irradiation conditions. The PL intensity increases monotonically with increasing the N concentration when the N concentration is above 2.6×10^16 cm^-3 , whereas no linear correlation between them does not appear below that N concentration. Although the PL intensity increases with increasing defects induced by ion irradiation, the PL quenching due to neighboring residual defects appear at above the areal vacancy concentration of 10^17 vac/cm^2 and the broad Raman scattering spectra originated from vibration modes of amorphized regions hinder the PL from NcVsi- centers at above 10^18 vac/cm^2. The formation mechanism and the charge state stability of NcVsi- centers are discussed based on the obtained results.

This paper reports optical properties of negatively charged NcVsi- centers in silicon carbide (a nitrogen substituting for a carbon atom adjacent to a silicon vacancy) whose emission wavelength is 1100-1500 nm at room temperature. High-purity semi-insulating (HPSI) 4H-SiCs are implanted with high energy N ion beams and subsequently thermally annealed to form NcVsi- centers. We investigated a wide range of N ion implantation dose using a micro ion beam implantation technique and observed the photoluminescence intensity from the SiC-NV centers. We show that under conditions of heavy implantation, the excitation laser power excites residual defects and their fluorescences interferes with the emission from the NcVsi- centers. These results allow us to clarify the requirements to optically detect isolated single NcVsi- centers at lightly implanted conditions.

We present a study of electrically active radiation-induced defects formed in 4H-SiC epitaxial layers following irradiation with fast neutrons, as well as 600 keV H+ and 2 MeV He++ ion implantations. We also look at electron emission energies and mechanisms of the carbon vacancy in 4H-SiC by means of first-principles modelling. Combining the relative stability of carbon vacancies at different sites with the relative amplitude of the observed Laplace-DLTS peaks, we were able to connect Z1 and Z2 to emissions from double negatively charged carbon vacancies located at the h- and k-sites, respectively.

4H-SiC pin-diodes are fabricated and the surface SPSs formed in the pin diodes are investigated using a confocal laser scanning fluorescence microscope (CFM). Locations where the surface SPSs appear as well as photoluminescence spectra of the observed surface SPSs are presented. Antibunching characteristics of the surface SPSs are also investigated by the second order autocorrelation function measurement. We conclude that two different types of surface SPSs appear in the surface of 4H-SiC. The location dependence of the observed surface SPSs indicates that the oxide layer on 4H-SiC plays an important role in the formation of surface SPSs, whereas neither ion implantation nor donor ions had an effect. The peak wavelength of luminescence spectra widely varies depending on their locations, indicating lattice strain introduced by the oxide layer has the potential to affect the luminescence spectra.