Strong Photoluminescence Enhancement in All-Dielectric Ge Thin Film Metasurfaces for Integration on the Si Platform

In this work, we demonstrate how germanium (Ge) all-dielectric metasurfaces can be leveraged to strongly enhance the radiative emission from Ge layers grown on silicon-on-insulator substrates by industry-standard processes. At room-temperature, the narrowband photoluminescence (PL) intensity is enhanced by a factor of ∼40× with respect to unstructured films. Power dependence analysis of the PL confirms direct band-to-band recombination as the dominant mechanism. According to full-wave simulation results, the emitted spectral intensity is well described by multipole modes of coupled Mie resonators, and can be tailored with respect to wavelength, polarization, and directivity by a suitable nanostructuring of the metasurface. This tunability-by-design, as well as the use of industry-standard processes and materials, bode well for the adoption within silicon electronic-photonic integrated circuit technologies for different applications, e.g., in local interconnects or photonic computing hardware.