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Letter

Nature Photonics 3, 59–63 (1 January 2009) | doi:10.1038/nphoton.2008.247

Monolithic germanium|[sol]|silicon avalanche photodiodes with 340|[nbsp]|GHz gain|[ndash]|bandwidth product

Yimin Kang , Han-Din Liu , Mike Morse , Mario J. Paniccia , Moshe Zadka , Stas Litski , Gadi Sarid , Alexandre Pauchard , Ying-Hao Kuo , Hui-Wen Chen , Wissem Sfar Zaoui , John E. Bowers , Andreas Beling , Dion C. McIntosh , Xiaoguang Zheng & Joe C. Campbell

Significant progress has been made recently in demonstrating that silicon photonics is a promising technology for low-cost optical detectors, modulators and light sources. It has often been assumed, however, that their performance is inferior to InP-based devices. Although this is true in most cases, one of the exceptions is the area of avalanche photodetectors, where silicon's material properties allow for high gain with less excess noise than InP-based avalanche photodetectors and a theoretical sensitivity improvement of 3|[nbsp]|dB or more. Here, we report a monolithically grown germanium|[sol]|silicon avalanche photodetector with a gain–bandwidth product of 340|[nbsp]|GHz, a keff of 0.09 and a sensitivity of |[minus]|28|[nbsp]|dB|[nbsp]|m at 10|[nbsp]|Gb|[nbsp]|s|[minus]|1. This is the highest reported gain–bandwidth product for any avalanche photodetector operating at 1,300|[nbsp]|nm and a sensitivity that is equivalent to mature, commercially available III–V compound avalanche photodetectors. This work paves the way for the future development of low-cost, CMOS-based germanium|[sol]|silicon avalanche photodetectors operating at data rates of 40|[nbsp]|Gb|[nbsp]|s|[minus]|1 or higher.