Abstract
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.
Highlights
Detection of infrared (IR) photons is an essential component of multifunctional optoelectronic technologies with versatile applications in different areas, from biosensing [1]and imaging [2] to optical communications [3] and computing [4]
Electrical analysis of a single unit cell of the device was conducted by the finite element method (FEM) using Lumerical’s DEVICE Simulation Suite to calculate the current-voltage characteristic (I-V curve) and bandwidth at room temperature, 300 K
Our results suggest that a higher bandwidth and responsivity could be achieved by changing the geometry and arrangement of the Ge nanoparticles
Summary
Detection of infrared (IR) photons is an essential component of multifunctional optoelectronic technologies with versatile applications in different areas, from biosensing [1]. Many semiconductors have a high refractive index in the NIR and visible range of the electromagnetic spectrum that leads to unique optical properties such as a non-radiating anapole state localizing the electric field inside semiconductor nanoparticles [10] Unlike their plasmonic counterparts with ohmic losses, semiconductor nanostructures have a higher conversion efficiency of photons to charge carriers [11,12,13]. Such unique properties in conjunction with their small sizes can lead to the design and fabrication of high speed, multifunctional, and cost-effective photodetectors. It shows zero-bias operation, small junction capacitance, and high shunt resistance
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