“…High-speed InP-based APDs are preferred over PIN-type photodetectors [ 10 ], particularly for conventional long-haul applications. The preferred solution in these situations is the separate absorption, grading, charge, and multiplication (SAGCM) structure, due to its low dark current [ 11 , 12 , 13 , 14 ], high quantum efficiency, and high gain-bandwidth product [ 15 , 16 , 17 ]. The importance of performance and reliability in these systems [ 18 , 19 ] has prompted research on epitaxy and device processing for the further development of high-performance and high-speed planar InP based SAGCM-APDs [ 20 , 21 , 22 , 23 , 24 ].…”