Ultra-fast germanium photodiode with 3-dB bandwidth of 265 GHz

By S. Lischke, A. Peczek, J. Morgan, K. Sun, D. Steckler, Y. Yamamoto, F. Korndorfer, C. Mai, S. Marschmeyer, M. Fraschke and 3 more. Nature Photonics, 2021

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On a scalable silicon technology platform, we demonstrate photodetectors matching or even surpassing state-of-the-art III–V devices. As key components in high-speed optoelectronics, photodetectors with bandwidths greater than 100 GHz have been a topic of intense research for several decades. Solely InP-based detectors could satisfy the highest performance specifications. Devices based on other materials, such as germanium-on-silicon devices, used to lag behind in speed, but enabled complex photonic integrated circuits and co-integration with silicon electronics. Here we demonstrate waveguide-coupled germanium photodiodes with optoelectrical 3-dB bandwidths of 265 GHz and 240 GHz at a photocurrent of 1 mA. This outstanding performance is achieved by a novel device concept in which a germanium fin is sandwiched between complementary in situ-doped silicon layers. Our photodetectors show internal responsivities of 0.3 A W−1 (265 GHz) and 0.45 A W−1 (240 GHz) at a wavelength of 1,550 nm. The internal bandwidth–efficiency product of the latter device is 86 GHz. Low dark currents of 100–200 nA are obtained from these ultra-fast photodetectors. By sandwiching a germanium fin between complementary in situ-doped silicon layers, a waveguide-coupled germanium photodiode with a 3-dB bandwidth of 265 GHz, accompanied by high responsivity and low dark current, is realized.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/82af59fb508a2b9df5d0a9a878cf9bfbb57c8d6b