High-speed flip-chip InP/InGaAs avalanche photodiodes with ultralow capacitance and large gain-bandwidth products

Abstract
Planar InP/InGaAs avalanche photodiodes (APDs) have been fabricated by adopting a flip-chart configuration and a monolithic lens structure. These APDs exhibit an ultralow capacitance of 70 fF, a quantum efficiency of 80%, a wide bandwidth of 7 GHz, and a large gain-bandwidth product of 80 GHz.