Metal-semiconductor-metal Ge photodetectors integrated in silicon waveguides

Metal-semiconductor-metal (MSM) Ge photodetectors integrated in silicon-on-insulator waveguides using butt coupling configuration have been experimentally demonstrated. Bandwidths reach 28GHz under 6V bias at wavelengths of 1.31 and 1.55μm for a photodetector with 1μm electrode spacing, which is almost compatible with a 40Gb∕s operation. High responsivity of about 1A∕W at both wavelengths for a 10μm long photodetector has been obtained. Under 1V bias, MSM photodetectors with 1 and 0.7μm electrode spacings have bandwidths of 9 and 17GHz, respectively, which is compatible with a data transmission speed of 10Gb∕s.