Germanium photodetectors for silicon microphotonics

We show that the direct epitaxial growth of Ge on Si is a viable technology for the integration of near-infrared photodetectors on Si for Si microphotonics. This conclusion is based on a study of the electronic properties of threading-dislocations in p-n junction and an experimental demonstration of the performance of Ge p-i-n photodiode made from Ge grown directly on Si. At 1.3 μm, we measured a responsivity of 550 mA/W. With the addition of SiO2 anti-reflection coating, we measured a maximum external responsivity of 770 mA/W.