A VLSI-COMPATIBLE HIGH-SPEED SILICON PHOTODETECTOR FOR OPTICAL-DATA LINK APPLICATIONS

A novel silicon photodetector suitable for high-speed, low-voltage ope ration at 780- to 850-nm wavelengths is reported. It consists of an in terdigitated p-i-n detector fabricated on a silicon-on-insulator (SOI) substrate by using a standard bipolar process. Biased at 3.5 V, this device attains a -3-dB bandwidth in excess of 1 GHz at lambda = 840 nm . The de responsivity measured at lambda = 840 nm on nonoptimized stru ctures ranges from 0.05 to 0.09 A/W, depending on the finger shadowing factor. A new approach for improving the responsivity is here propose d and quantitatively analyzed. The fabricated devices exhibit extremel y Low dark currents, small capacitance, large dynamic range, and no ev idence of low-frequency gain. The overall performance and process comp atibility of these photodetectors make them viable candidates for the fabrication of silicon monolithic receivers for fiber-optic data links .