High-performance waveguide-integrated germanium PIN photodiodes for optical communication applications [Invited]

This paper reports on high-performance waveguide-integrated germanium photodiodes for optical communications applications. 200 mm wafers and production tools were used to fabricate the devices. Yields over 97% were obtained for three different compact photodiodes (10×10  μm and intrinsic region width of 0.5, 0.7, and 1 μm) within the same batch of three wafers. Those photodiodes exhibit low dark currents under reverse bias with median values of 74, 62, and 61 nA for intrinsic widths of 0.5, 0.7, and 1 μm, respectively, over a full wafer. Responsivities up to 0.78  A/W at 1550 nm and zero bias were measured. Zero bias operation is possible for 25 and 40 Gbps with receiver sensitivity estimated to −13.9 and −12.3  dBm, respectively.