Design of Metasurface-Based Photodetector with High-Quality Factor

The ability of fine-tuning wavelengths in a high-Q resonance has been applied to various optical applications, particularly that of the development of nanoscaled, ultrathin photodetectors that realize next-generation optical sensors. However, designing a nanopatterned surface in a photodetector to induce intriguing optical effects inevitably deteriorates the electrical properties due to the increased roughness and defects, which cause the significant recombination of the photogenerated carriers. Moreover, light absorption in a semiconductor fundamentally decreases the Q factor of a resonance and ultimately limits the spectral sharpness. Thus, there is a trade-off between the applications of nano-optics for the fine control of wavelengths and the matured photodetector platform for electrical stability. In this work, we propose an alternative type of optical design for a photodetector by effectively decoupling the functionality of nano-optics for high-Q resonances and the electrical properties of semiconductors for the extraction of efficient photocarriers. By optimally balancing the loss of scattered radiation in a high-Q resonance and the loss of absorption in a semiconductor, we achieve a nano-optics-based photodetector with high-Q absorption and polarization sensing without a significant deterioration in the electrical properties. We believe that the suggested design rule can be effectively applied for the realization of emerging nanoscaled photodetectors for various applications of next-generation optical sensors.