Ge Photodiode with -3 dB OE Bandwidth of 110 GHz for PIC and ePIC Platforms
Stefan Lischke, Anna Pęczek, F. Korndörfer, Christian Mai, H. Haisch, Michael Koenigsmann, M. Rudisile, Daniel Steckler, F. Goetz, Mirko Fraschke, S. Marschmeyer, Andreas Krüger, Y. Yamamoto, D. Schmidt, Ulrike Saarow, P. Heinrich, Aleksandra Kroh, Markus Andreas Schubert, Jens Katzer, P. Kulse, A. Trusch, Lars Zimmermann
Abstract
We present an SOI-waveguide coupled germanium photodiode with very high OE -3 dB bandwidth of ≥110 GHz at reverse bias of 2 V. This performance is achieved by a novel construction in that the germanium is sandwiched in between two in-situ doped silicon regions. This fabrication approach allows for avoiding ion-implantation into the germanium, which is certainly beneficial for the bandwidth as minority carrier diffusion effects are strongly suppressed. A responsivity of >0.6 A/W at 1550 nm (-2 V) is achieved, while the dark current of this device yields to about 300 nA (-2 V). To our knowledge, this is the most advanced germanium photo detector in terms of bandwidth combined with state-of-the-art responsivity as well as moderate dark currents. We demonstrate that the novel photodiodes can be fabricated with high yield.