Highly Efficient Near-Infrared Detector Based on Optically Resonant Dielectric Nanodisks

• Main Authors: Reza Masoudian Saadabad, Christian Pauly, Norbert Herschbach, Dragomir N. Neshev, Haroldo T. Hattori, Andrey E. Miroshnichenko
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Nanomaterials
• Subjects: NIR photodetector; bandwidth; dielectric nanodisks
• Online Access: https://www.mdpi.com/2079-4991/11/2/428

Fast detection of near-infrared (NIR) photons with high responsivity remains a challenge for photodetectors. Germanium (Ge) photodetectors are widely used for near-infrared wavelengths but suffer from a trade-off between the speed of photodetection and quantum efficiency (or responsivity). To realize a high-speed detector with high quantum efficiency, a small-sized photodetector efficiently absorbing light is required. In this paper, we suggest a realization of a dielectric metasurface made of an array of subwavelength germanium PIN photodetectors. Due to the subwavelength size of each pixel, a high-speed photodetector with a bandwidth of 65 GHz has been achieved. At the same time, high quantum efficiency for near-infrared illumination can be obtained by the engineering of optical resonant modes to localize optical energy inside the intrinsic Ge disks. Furthermore, small junction capacitance and the possibility of zero/low bias operation have been shown. Our results show that all-dielectric metasurfaces can improve the performance of photodetectors.