A membrane platform for enhancing the emission of color centers in 4H-SiC with photonic resonators*

4H-silicon carbide (SiC) has recently emerged as a promising platform to host point defects with possible applications in quantum technologies, such as distributed quantum computing or sensing. Single silicon-vacancy centers in 4H-SiC have already shown to comprise desirable properties in this regard, such as nearly-lifetime-limited optical linewidths, photon indistinguishability and spin coherence times on the order of ms at low temperatures [1,2]. However, light emitted from such color centers typically is collected very inefficiently when using confocal microscopes and unstructured samples (< 1% collection efficiency) due to the high refractive index of the material. Additionally, silicon-vacancy centers in 4H-SiC show only a small fraction of emission into the zero-phonon line (~8-9%) [3]. To overcome these limitations, we make use of a platform based on (sub-)µm-thin membranes in 4H-SiC, created by lapping, chemical-mechanical polishing and reactive-ion-etching of bulk material, with two different approaches: Firstly, we directly fabricate photonic resonators from sub-µm-thin membranes and secondly, we want to integrate µm-thin membranes into open-access Fabry-Pérot cavities. Here, we report on recent updates of our work including the fabrication of membranes with integrated color centers and a characterization of their optical properties for different membrane thickness.

[1]: Babin, C. et al., Nat. Mater. 21, 67-73 (2022)

[2]: Morioka, N. et al., Nat Commun 11, 2516 (2020)

[3]: Udvarhelyi, P. et al., Phys. Rev. Applied 13:054017 (2020)