Activation and control of visible single defects in 4H-, 6H-, and 3C-SiC by oxidation

Abstract

In this work, we present the creation and characterisation of single photon emitters at the surface of 4H- and 6H-SiC, and of 3C-SiC epitaxially grown on silicon. These emitters can be created by annealing in an oxygen atmosphere at temperatures above 550 °C. By using standard confocal microscopy techniques, we find characteristic spectral signatures in the visible region. The excited state lifetimes are found to be in the nanosecond regime in all three polytypes, and the emission dipoles are aligned with the lattice. HF-etching is shown to effectively annihilate the defects and to restore an optically clean surface. The defects described in this work have ideal characteristics for broadband single photon generation in the visible spectral region at room temperature and for integration into nanophotonic devices.

Silicon carbide color centers for quantum applications

“…The defects found at the SiC/SiO 2 interface responsible for SPS are not yet fully identified. The passivation by thermal oxidation in the oxygen atmosphere up to 800°C leads to a significant increase of their surface emitters density, as reported in [93]. The C face also has almost an order higher density of defects than the Si face.…”

“…However, further studies have found that similar emission can be achieved by the oxidation process in all polytypes 3C, 4H and 6H and by annealing. The defect labeled 'Oxidation related' in [26] of polytype 3C, 4H and 6H, is studied in [93]. It has ZPL 564-690 nm, with the largest PL intensity 800 kcts s −1 .…”

“…Some emitters were blinking, and high-temperature oxidation was stabilizing the emission. SPSs with similar properties but very close to the surface of the SiC were formed by annealing in oxygen at 800°C [93]. These emitters were designated as a surface-related defect with ZPLs that were distributed throughout the visible spectral region from 545 to 750 nm, with 3-5 ns lifetime and maximum 800 kcts s −1 saturation count rate.…”

“…The SPEDs exhibited emission throughout the visible spectral region from 560 to 850 nm, maximum count rate over 350 kcts s −1 albeit without observing saturation. These defects are supposed to be related to other interface defects [93] which were also found in the diode in optical excitation, however, their photo-physics differs substantially, as for example the SPED have a plateau in the g (2) at zero delay time and much less photon bunching is observed. It was also observed that the SPED had a photo-physics resembling a 4-levels system, with an additional excited state [22].…”

“…Data for V Si are from [54, 56, 58, 60, 62, 69-73, 76-79, 147]; DV from [53, 55, 81-85]; IR unknown emitters from [52]; CAV form [49, 87-90, 92]; D1 color centre from [22] and related references. ; oxydation related defects from[93]; annealing related from[51]; N C V Si from[43,44,[94][95][96]; Ti from[100]; Cr from[45,101,102]; V from[45][46][47]103]; Mo from[45,48].…”