Capacitance in Waveguide-Integrated Hydrogenated Amorphous Silicon p-i-n Diodes for Active Photonic Devices

With the increasing bandwidth requirement in computing and signal processing, the inherent limitations in metallic interconnection are seriously threatening the future of traditional integrated circuits (ICs) industry. Silicon photonics can provide a low-cost approach to overcome the bottleneck of high data transmission rate by integrating into an electronic IC a photonic layer. This attractive perspective has given in the last years a huge impetus to the development of CMOS photonics, and, recently, few commercial devices have been proposed. Hydrogenated amorphous silicon (a-Si:H) has emerged as a promising material to provide microchips with passive and active photonic functions through a fully CMOS compatible technological process. In this paper, we present an overview about the performances achieved by our group with different configurations of a-Si:H based electro-optical amplitude modulators integrated into passive waveguides. Moreover, new experimental results and physical explanations for measured small-signal capacitance of forward biased waveguide-integrated a-Si:H p-i-n diodes are also discussed.