Single Color Centers in Silicon Carbide: electro-optical access via epitaxial graphene
Final Report Abstract
Color centers in silicon carbide (SiC) are interesting quantum systems for photonic quantum technologies. Compared to diamond, SiC provides the possibility to technologically link electronic and optical signals on the same platform. In the project "Single color centers in silicon carbide: electro-optical access using epitaxial graphene", we investigated the role that graphene could play, which grows epitaxially on the (0001) face of 4H-SiC in very good quality. As a first step, we created new optically active point defects by ion implantation. In particular, we have identified two new defects (TS defect and DI defect) that are formed when annealing at very high temperatures. We were able to follow a sequential defect formation with increasing annealing temperature. Both point defects have special, very interesting properties. We used epitaxial graphene on the SiC surface for these studies to suppress interfering luminescent surface defects. The use of graphene electrodes significantly strengthens the portfolio of experimental methods. These electrodes are largely transparent and one can fine-tune an underlying defect such as the silicon defect VSi in its characteristic wavelength without affecting its symmetry. This will become important if one wants to tune only nearly identical color centers to an identical wavelength. If one considers silicon imperfections between two oppositely charged electrodes, they are subjected to a lateral symmetry-reducing field that can be used for spectral splitting. Using four graphene electrodes (quadrupole), a spatial profile of the excitation vector can be measured by varying the direction of irradiation and emission and the strength of the electric field. Using the TS defect as an example, it could be shown that it has an excitation vector connecting the next nearest neighbors in the SiC crystal. Overall, transparent graphene electrodes have been shown to be a valuable addition to the method portfolio for the optical study of color centers, allowing in particular electrostatic manipulation of the optical properties of color centers.
Publications
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Sub-Bandgap Photoluminescence Study on Implantation-Induced Color Centers in 4H-SiC, International Conference on Silicon Carbide and Related Materials 2017, Washington DC, USA
Maximilian Rühl
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Controlled generation of intrinsic nearinfrared color centers in 4H-SiC via proton irradiation and annealing, Applied Physics Letters, 113 (2018) 122102
M. Rühl, C. Ott, S. Götzinger, M. Krieger, H.B. Weber
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Control of the Photoluminescence of the Silicon Vacancy in 4H Silicon Carbide by Electric Fields, International Conference on Silicon Carbide and Related Materials 2019, Kyoto, Japan
Maximilian Rühl
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Stark Tuning of the Silicon Vacancy in Silicon Carbide, Nano Lett, 20 (2020) 658-663
M. Rühl, L. Bergmann, M. Krieger, H.B. Weber
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"Intrinsic color centers in 4H-silicon carbide formed by heavy ion implantation and annealing". Journal of Physics D (2021)
Takuma Kobayashi, Maximilian Rühl, Johannes Lehmeyer, Leonard Zimmermann, Michael Krieger, and Heiko B. Weber
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Removing the orientational degeneracy of the TS defect in 4H-SiC by electric fields and strain, New Journal of Physics, 23 (2021) 073002
M. Rühl, J. Lehmeyer, R. Nagy, M. Weisser, M. Bockstedte, M. Krieger, H. B. Weber
