Evolution of the optically detected magnetic resonance spectra of divacancies in 4<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>H</mml:mi></mml:math>-SiC from liquid-helium to room temperature

The divacancies in 4<a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mi>H</a:mi></a:math>-SiC attract significant attention for use as qubits owing to their spin and photoluminescence (PL) properties and near telecom PL emission. Nevertheless, there exist some ambiguities in the interpretation of their optically detected magnetic resonance (ODMR) spectra, especially at elevated temperatures. In this study, we investigate the divacancy configurations PL1–PL7 using PL and ODMR. We record the full temperature dependence between liquid-helium temperature (3.8 K) and room temperature (295 K), obtained with two different laser energies and different laser polarizations. We also present PL data recorded simultaneously with the ODMR. Our study allows us to continuously follow the evolution of all divacancy configurations in ODMR with temperature, even though their signature is not distinguishable in PL at elevated temperatures. We identify all lines in the room-temperature ODMR spectrum and show that a hypothetical defect PL7, assumed in earlier work to stem from another divacancy configuration, does not exist and its ODMR signal at room temperature is fully explained with PL4. We also provide direct PL evidence on the spatial distribution of PL5, PL6, and a new PL3a defect, showing their presence only close to the surface of the sample, thus corroborating their association with divacancies near stacking faults. We address also the role of the upconversion of the photoluminescence in the ODMR spectra observed at higher temperatures.