Pure Silicon - High Performance! Advanced Optical Receivers in Standard Silicon BiCMOS Technologies

We present the state of the art of integrated silicon photodetectors and circuits by concentrating on the progress in the last decade. Especially three highlights will be presented in more detail. In this paper a vertical pin-photodiode in a 0.6 mu m BiCMOS technology, consisting of an n-buried cathode, an n(-) epi layer, and a p(+) anode will be discussed. The measured responsivities for different wavelengths are 0.33A/W @ 850nm and 0.46A/W @ 660nm, respectively. Really outstanding is the reached speed of the photodiodes. The -3dB cut-off frequencies of these 50x50 mu m(2) diodes are up to 2.1GHz @ 850nm light and up to 3GHz @ 660nm light, depending on the reverse bias voltage. This high performance photodiode allows the competition of pure silicon optoelectronic integrated circuits (OEICs) even with GaAs OEICs. A silicon OEIC reaches at 2.5Gb/s(1) a higher sensitivity than a GaAs OEIC2. It also consumes less power and a remarkably smaller chip area. Massive parallel integration of optical receivers enables an extremely high total data rate. A new OEIC consisting of 45 parallel channels with a data rate of 3Gb/s @ 850nm each allows an overall data rate of 135Gb/s.