Reliability Challenges of Nanoscale Avalanche Photodiodes

Figure 1 shows the general device schematics and electric field profile of an APD device. For the top-illumination APD illustrated in Figure 1, the top layer is a heavily p-doped InGaAs layer that forms Ohmic contact with the p-metal. The next is an intrinsic In0.53Ga0.47 as absorption layer, which has a band gap energy of 0.75eV, used to absorb light [5]. To achieve lattice match to InP substrate, InAlAs is widely used for the field control and multiplication layers. The electric field reaches the maximum in the multiplication layer that is responsible for avalanche breakdown operation [4]. The doping of the InAlAs field control layer can affect the relative field strength between the absorber and multiplication regions.